Using Seaweed to get rid of nuisance algae in your aquarium or pond

[Subsea]

9 watts will increase your water temps??? How much gallonage is your system?
What about the cascading/cooling evaporate of the water?
If it's an up flow setup, the aeration should cool things so, 9 watts should be manageable. In my mind anyway.

9 watts is 30.69 btu's.
Put that into 10 gallons of tank water and it will take 2.8 hours to raise the temp 1 degree F.
I have been drinking a lot, so my math or my process might be wrong.

Edit:
I see you have 75 gallons listed in your sig. Is that total system volume or the size tank you have?

I think that your math is correct. For people worried about temperature in our reef tanks, consider evaporative cooling. One BTU is defined as the heat required to raise one pound of water one degree farinheit. When one pound of water evaporates, then 1000 BTU of cooing take place. When one gallon of water evaporates, 8340 BTU of cooling takes place. A 4" Dia muffin fan will cool off a big tank.

 

[SantaMonica]

I am curious what you think about this research

Sounds like a good topic for another thread

So, is it in essence a counter flow scrubber? Producing skim mate?

First time I've heard of upflows called that

Although it's not a waterfall... the upflowing bubbles should not produce skimmate if they are big and rapid enough. Skimmers use tiny, foamy bubbles.

How cool would it be if a skimmer could be crossed with a scrubber?

Been drawn up already But as stated, they use different size bubbles.

What about the cascading/cooling evaporate of the water?

The pole version of the waterfall, should have good cooling/evap.

If it's an up flow setup, the aeration should cool things so

Actually upflows don't evaporate or cool very much at all.

the size of the growing surface (and lighting) is dependent on the [feeding] within the system

True. However the unique nature of this pole version of the waterfall requires that it be stable and not fall over, and also that it "catch" as much light from the lights as possible. So, a pole version will probably be bigger than the feeding guideline indicates for smaller tanks. A 4" diameter pole is probably the smallest you can go.

but as long as algae is growing, it will do the same job 1/4" long or 4" long.

Longer is always better. If it does not detach. Because it give more photosynthetic surface area to the lights, among other things.

 

[Subsea]

I looked at it, what would you like to know? Maybe your after another's opinion?

I see nothing we don't already know. The more trophic an area becomes, the more algae grows.
I also see that man has interfered with nature to attain data results. A tent reguardless of what it's made of can't be used in my opinion to get test readings. No matter how much you think the tent doesn't interfere with the results. It will. Water and nutrients simply won't flow in the same manner as in the open water. You can't rush what the future brings us. There is a whole lot of things that can happen to change or shift the educated guess inside the tent.
Place a tent on a "really old sand bed" and guess how things will happen in a very short time frame is not cool. Heck, who knows what life will step into play and take on another role as things happen slowly.

Maybe, just maybe.....instead of striving to fill the screen with green. We use an algae scrubber as a metric (an indicator) as to what the real value of the nutrient load of our systems truly is? Just cause algae has the ability to read zero on a hobby grade test kit. Doesn't mean we have to run it on the very edge of its ability.
What if the scrubber was just simply there to capture the ebb and flow of life within our systems? Maybe a tank sitters heavy hand feeding the tank? A power outage that didn't get attended to fast enough?
Just simply give algae a place to grow if it needs to based on elevated nutrient levels within said system.

I am trying to understand your comments about the referenced book, "Coral Reefs in Microbial Seas". Where did the tent analogy come from? The study included 20 pHD scientist over 15 years of research. If you truly seek knowledge, look at the references at the end of the book.

 

[2_zoa]

I am trying to understand your comments about the referenced book, "Coral Reefs in Microbial Seas". Where did the tent analogy come from? The study included 20 pHD scientist over 15 years of research. If you truly seek knowledge, look at the references at the end of the book.

If you click the link given, it will take you to the abstract. It also has a couple free images.
Click the image that looks like a pyramid. It's captions state that it's a tent over benthic life. It's equipped with a pump, a data logger, and a sample bottle.
There's also a bar graph that shows a calculated reef and the tent reference.

Now, since you bring up that there was 20 scientists involved over a 15 year period. I have to wonder how much of the info can be trusted? That's a lot of opinions and a long time to argue each other's thoughts on any readings or results.
I also have to ask why it went 15 years? (Given I know nothing about the study)
Was it funding? Or was it actually planned to go 15 years? That was EXPENSIVE!
Was the study done on a consistent basis? Or was it done spuratically and the data points merged together? Different times of the year?
The book must be a colabration of the referecnces you mentioned?

Did I post shooting from the hip? Yes I did.
Should I read the book? Maybe. I personally feel there was to much involvement to get accurate info.

Asking WHY is where one gains knowledge in my opinion. Not through references. You might get a little more close by going through the references yet, (again) in my opinion. You are still at the mercy of who wrote the data or conducted the collection of the data. Then your at the mercy of what it is that they feel is important with in said data to bring forward a presentation. Go sit and listen to a speaker and, your subject to what they feel is important. Go listen to another speaker on the same information......you'll walk away with a different mindset of the topic. Kinda like the stock market right? Take two groups of investors. One group from Harvard and the other group from Yale. They both read the exact same information and yet the two groups will draw two different investing strategies because the information simply isn't complete enough to make a truly informed decision.

I believe that we as humans can only go by what makes sense to us. Each individual that is. Research and discussion is what will make each person act on what they feel to be the best option. I don't feel there are any embarrassments within our actions. Everyone can learn from watching as well. Take my post for instance, it drew you out to ask questions. Now more are thinking and I believe that's a good thing.
(They could be thinking I'm an idiot!!!!)

 

[Subsea]

If you click the link given, it will take you to the abstract. It also has a couple free images.
Click the image that looks like a pyramid. It's captions state that it's a tent over benthic life. It's equipped with a pump, a data logger, and a sample bottle.
There's also a bar graph that shows a calculated reef and the tent reference.

Now, since you bring up that there was 20 scientists involved over a 15 year period. I have to wonder how much of the info can be trusted? That's a lot of opinions and a long time to argue each other's thoughts on any readings or results.
I also have to ask why it went 15 years? (Given I know nothing about the study)
Was it funding? Or was it actually planned to go 15 years? That was EXPENSIVE!
Was the study done on a consistent basis? Or was it done spuratically and the data points merged together? Different times of the year?
The book must be a colabration of the referecnces you mentioned?

Did I post shooting from the hip? Yes I did.
Should I read the book? Maybe. I personally feel there was to much involvement to get accurate info.

Asking WHY is where one gains knowledge in my opinion. Not through references. You might get a little more close by going through the references yet, (again) in my opinion. You are still at the mercy of who wrote the data or conducted the collection of the data. Then your at the mercy of what it is that they feel is important with in said data to bring forward a presentation. Go sit and listen to a speaker and, your subject to what they feel is important. Go listen to another speaker on the same information......you'll walk away with a different mindset of the topic. Kinda like the stock market right? Take two groups of investors. One group from Harvard and the other group from Yale. They both read the exact same information and yet the two groups will draw two different investing strategies because the information simply isn't complete enough to make a truly informed decision.

I believe that we as humans can only go by what makes sense to us. Each individual that is. Research and discussion is what will make each person act on what they feel to be the best option. I don't feel there are any embarrassments within our actions. Everyone can learn from watching as well. Take my post for instance, it drew you out to ask questions. Now more are thinking and I believe that's a good thing.
(They could be thinking I'm an idiot!!!!)

I was more interested in your point of reference. Yes, I think you should read the book to be more informed to truely criticize it. Martin Moe back in the 1960, in essence said what the book said but did not have the scientific measuring tools to prove it. Julian Sprung and Charles Delbric in Reef Aquarium 3 pointed out similiar findings.
It is always about the bugs. They are the "microbial overlords" in our reef tanks and, for that matter, the world. Just ask the Martians in War of the Worlds.

 

[2_zoa]

I was more interested in your point of reference. Yes, I think you should read the book to be more informed to truely criticize it. Martin Moe back in the 1960, in essence said what the book said but did not have the scientific measuring tools to prove it. Julian Sprung and Charles Delbric in Reef Aquarium 3 pointed out similiar findings.
It is always about the bugs. They are the "microbial overlords" in our reef tanks and, for that matter, the world. Just ask the Martians in War of the Worlds.

My apologies if I came across as being critical about the book.

As I stated, we all do or act on what makes sense to us. It's pretty well known that bugs are important. I personally don't feel that reading the book will make me think any differently about a diversified population. I have done as much as I could to get my tank as full of critters as I could. I enjoy watching the ones I can see. If one isn't careful, the bugs if driven improperly in a tank can kill the tank. So they must be respected just like anything else. You yourself have expounded about the life in your seaweed grow operation. People using algae scrubbers can be plagued by critters. Pods can eat a hole right in the algae they're trying to grow. Dose a tank with a carbon source without proper precautions, you'll remove all the oxygen by growing the bacteria population. Anything can become a nuisance. Be it algae or bugs or whatever. Life ebbs and flows just like the tides. Maybe that's why Sprung and Delbrik came to "similar" findings. Life was Ina different place. Maybe it's because of the better technology. You yourself having read those pieces of literature and you can't answer those questions. Proving what I stated in my other post about human involvement and interpretation. Especially (in my opinion) an interpuration of many others ideas or published points of view of importance.

I am my own "bug" and I can't predict my future. Nor can I guess how I'm going to react to the next thing that comes at me. What I DO KNOW, is what I've lived and learned. That's the best reference there is. Even that gets shady as my life goes on.
So, tell me. How am I to make an educated decision based on a reference? When said reference is based on what "we think" we know of some other organisms life, based on its past ((referecnces) someone else's opinion) that we are trying to follow/figure out by placing a tent over an area and collecting samples? Or any other data collection process that may be. How many critters are far to fragile to deal with those actions that we don't know about?

There was a time that we had 9 planets in our solar system.
All I'm trying to say is to question what is fact. What it is that is "known". I'm not critizing the book or anybody involved. Just asking the question why. Why did they come to those conclusions? What technology did they have behind them?
I ask people all the time. What calibrates the calibration machine?

 

[SantaMonica]

Here is a video of roughing:
https://vid.me/hCKb


...and the result:

 

[ratherbeflyen]

Quite the opposite in fact - algal attachment strength is critical to the effectiveness of a scrubber. If it wasn't, then roughing up the screen would be much less important, but it is.

Regarding the length of the strand, this too is an important point to understand. A 1/4" strand only has so much area to absorb light and nutrients. A 4" long strand would have 16x that area (edited...Sunday Math). The primary production of a longer strand of algae is therefore much larger - the larger a mass of algae gets, the more production occurs, and it works at a somewhat exponential rate.

Longer is always better. If it does not detach. Because it give more photosynthetic surface area to the lights, among other things.

I agree that longer algae is indeed better. My point is that long algae is not a requirement in order to have a "successful" scrubber. I think we get too hung up on what the growth looks like. What's important is the water quality and display tank condition. If 4" algae is 16x better than 1/4" algae, then a screen 16x bigger would in theory export the same nutrients with 1/4" algae. Even if it breaks off with anything longer than 1/4" it will most likely end up in another filter, sock, floss, skimmer etc. at which point the nutrients are removed. Unless your space limited or something, then a larger surface area and shorter, weaker attached algae does the same job. I don't care if my scrubber only grows black slime or purple unicorns. If the water has no nitrite, nitrate, or phosphate I'll take the purple unicorns.

 

[Floyd R Turbo]

I think we get too hung up on what the growth looks like. What's important is the water quality and display tank condition.

This is very true

If 4" algae is 16x better than 1/4" algae, then a screen 16x bigger would in theory export the same nutrients with 1/4" algae. Even if it breaks off with anything longer than 1/4" it will most likely end up in another filter, sock, floss, skimmer etc. at which point the nutrients are removed.

yes, but if detached algae gets stuck in a sock or floss and that is not changed for several days, that algae can release it's adsorbed nutrients back into the water column

Unless your space limited or something, then a larger surface area and shorter, weaker attached algae does the same job.

Anecdotal evidence has shown that this is only really true to a certain point. Generally speaking, if you size a screen much more than 2x oversized compared to what you are feeding, the algae tends to try to fill in the whole screen but can't, and you end up growing a lot of slime or yellow spongy growth, which doesn't filter as effectively. There are a lot of factors that go into screen sizing besides feeding rate but that is the primary one.

Taking it to the extreme, if you fed 2 cubes/day then a 4x6 screen would suffice and should grow GHA well, but putting in a 12x18 screen (which is good for 18 cubes/day) would likely not grow GHA very well at all, if it was provided flow and lighting appropriate for an 18 cube/day scrubber, because that is way too much light and the nutrients aren't there to support algae growth across the whole screen. So rather than end up with a thin carpet of GHA, you would likely end up with a screen with no GHA and just a bunch of slime. If you scaled back the lighting so that it was more in line with what you are feeding, then you would be spreading the light out too thin, which would likely result in very weak growth, and probably very dark. Also that's a high flow requirement for that size of screen, so now we're talking overall system efficiency (meaning, you're putting a lot of energy into a screen that is not doing a very good job). If you dial the flow back, you might get uneven coverage.

The point is, there are many reason to not oversize too much.

I don't care if my scrubber only grows black slime or purple unicorns. If the water has no nitrite, nitrate, or phosphate I'll take the purple unicorns.

I get what you're saying, but when you get primarily funky types of growth, you can get some other unwanted side effects. Some inhabitants of the system might react negatively to a large scrubber that is only growing yellow spongy slime growth or dark brown/black slime.

 

[ratherbeflyen]

yes, but if detached algae gets stuck in a sock or floss and that is not changed for several days, that algae can release it's adsorbed nutrients back into the water column

Agreed, but that is a husbandry/maintenance problem not a scrubber problem. It also takes a long time for the algae to break down, and some if not all of the nutrients released would be reabsorbed by the algae remaining in the scrubber.

Anecdotal evidence has shown that this is only really true to a certain point.... The point is, there are many reason to not oversize too much.

Agreed, the 16x analogy was more for easy math than sound sizing advice. My point is a scrubber still has benefits even if it never grows 4" gha.

I get what you're saying, but when you get primarily funky types of growth, you can get some other unwanted side effects. Some inhabitants of the system might react negatively to a large scrubber that is only growing yellow spongy slime growth or dark brown/black slime.

Again I agree. You can't just stick a light bulb in the corner and expect it will create/solve all your tank requirements. Which is why I believe the purple unicorn scrubber is a great addition IF it cleans your water and maintains your display tank. If purple unicorns keep your water clean but has your display covered in cyano and dyno, or eats your fish then it's not working.

Long green hair algae may be the most desired and beneficial type, but your scrubber is not a failure just because you don't have it. If the tank is clean, healthy, and has thriving fish/coral. Then your scrubber is a success and it doesn't matter if it's gha or purple unicorns.

This 2" pvc up flow scrubber I had in my quarantine tank I consider a success. I kept 7 fish in this tank for ~3 months while I treated a white spot outbreak with hyposalinity. The only filtration I had was some rubble in a 2 liter bottle with an air stone, and the up flow scrubber. The scrubber never grew very long algae, but all my fish survived the white spot parasite did not. I was going to leave a couple fish in that tank and do some algae experiments, but the heater failed and I didn't have a spare. I have no doubt that a couple fish would be just fine in that tank for months or longer with no water changes using only that scrubber and rock with occasional bottom cleaning.

The point being, an algae scrubber does not have to grow long green hair algae with amazing attach points to be beneficial. I make no argument that it's in any way bad to have long green hair algae, but it's not an absolute requirement to have it.

 

[Floyd R Turbo]

I just spent 10 minutes searching for an image that appropriately reflected the term "Purple Unicorn Scrubber" but came up empty handed....

 

[ratherbeflyen]

Here ya go, one purple unicorn that will solve all your problems.

 

[SantaMonica]

Anyone try the grinding/cutting the pipe yet?

 

[jason2459]

Anyone try this yet?

 

[2_zoa]

Anyone try this yet?

I myself would not. The design itself lends to a mess in my mind. All splashing of the dreaded salt water will be everywhere. Kinda why I thinks the "zero edge" tanks didn't show up all over and dominate the industry......
Never mind the fact that an outside diameter is just hard as heck to light. You'd need at least 4 times the lighting to achieve the same result......

 

[HammerLover]

I have 2 gallon modded fuge that has a nice combo of hair algae, cyano and grape caulerpa. Fuge is lit 24/7 and all of them are growing crazy. I remove 75% of the algae every week and after 4 days they are back in being lush and green. Pods also love the fuge

 

[SantaMonica]

Phosphate flow out of rocks

Many people, when they get their scrubber running for the first time, get worried when more (not less) algae starts to grow on their rocks. It seems really strange, especially when nitrate and phosphate have gone lower than before. What is happening is that phosphate is coming out of the rocks. Remember, phosphate is invisible, so you can only see the effects of it, and it always "flows" from higher concentrations to lower concentrations (just like heat does).

Example: If your room is warm, and you put a cold object on the floor, heat from the air in the room will "flow" into the object until the object and the air are the same temperature. Example 2: If you put a hot object on the floor, heat will "flow" out of the object and go into the air in the room, again, until the air and the object are the same temperature. Now suppose you open your windows (in the winter). The warm air in your room will go out the windows, and it will get colder in the room. The object on the floor is now warmer than the air, so heat will flow out of the object and into the air, and then out the window.

Think of phosphate as the heat, and your rocks as the object, and your windows as the scrubber. As the scrubber pulls phosphate out of the water, the phosphate level in the water drops. Now, since the phosphate level in the water is lower than the phosphate level in the rocks, phosphate flows from the rocks into the water, and then from the water into the scrubber. This continues until the phosphate levels in the rocks and water are level again. And remember, you can't see this invisible flow.

This flow causes an interesting thing to happen. As the phosphate comes out of the rocks, it then becomes available to feed algae as soon as the phosphate reaches the surface of the rocks where there is light. So, since the surface of the rocks is rough and has light, it starts growing MORE algae there (not less) as the phosphate comes out of the rocks. This is a pretty amazing thing to see for the first time, because if you did not know what was happening you would probably think that the algae in the scrubber was leaking out and attaching to your rocks. Here are the signs of phosphate coming out of the rocks:

1. The rocks are older, and have slowly developed algae problems in the past year.

2. The scrubber is new, maybe only a few months old, and has recently started to grow well.

3. Nitrate and phosphate measurements in the water are low, usually the lowest they have been in a long time.

4. Green hair algae (not brown) on the rocks has increased in certain spots, usually on corners and protrusions at the top.

5. The glass has not needed cleaning as much.


Since skimmers, filter socks, etc don't remove any nitrate and phosphate, and waterchanges and macro's in a fuge don't remove much, most people have never seen the effects of large amounts of phosphate coming out of the rocks quickly. But sure enough, it does. How long does it continue? For 2 months to a year, depending on how much phosphate is in the rocks, how strong your scrubber is, and how many other phosphate-removing filters you have (GFO, carbon dosing, etc). But one day you will see patches of white rock that were covered in green hair the day before; this is a sure sign that the algae are losing their phosphate supply from the rocks and can no longer hold on. Now it's just a matter of days before the rocks are clear.

 

[SantaMonica]

Advanced Aquarist Feature Article for December 2013: Coral Feeding: An Overview
http://www.advancedaquarist.com/2013/12/aafeature


The picture in the article shows that in the 1000 litre test tank:

98% of the food particles go to the skimmer when there are 2 coral colonies
71% of the food particles go to the skimmer when there are 40 coral colonies
92% of the food particles go to the skimmer when there are 2 coral colonies, when skimming is cut in half
55% of the food particles go to the skimmer when there are 40 coral colonies, when skimming is cut in half


"This trade-off between food availability and water quality can be circumvented by using plankton-saving filtration systems, which include [...] algal turf scrubbers" [like the DIY pole version]

"Corals are able to feed on a wide range of particulate organic matter, which includes live organisms and their residues and excrements (detritus)."

"...bacteria [...] can be a major source of nitrogen." [corals need nitrogen]

"...when dry fish-feed or phytoplankton cultures are added to an aquarium, a part of this quickly ends up in the collection cup of the skimmer.

"...mechanical filters (which can include biofilters and sand filters) result in a significant waste of food."

"Detritus is a collective term for organic particles that arise from feces [waste], leftover food and decaying organisms. Detrital matter is common on coral reefs and in the aquarium, and slowly settles on the bottom as sediment. This sediment contains bacteria, protozoa, microscopic invertebrates, microalgae and organic material. These sedimentary sources can all serve as coral nutrients when suspended, especially for species growing in turbid waters. Experiments have revealed that many scleractinian corals can ingest and assimilate detritus which is trapped in coral mucus. Although stony corals may ingest detritus *when* it is available, several gorgonians have been found to *primarily* feed on suspended detritus."

"Dissolved organic matter (DOM) is an important food source for many corals. [...] scleractinian corals take up dissolved glucose from the water. [algae produces glucose] More ecologically relevant, corals can also absorb amino acids and urea from the seawater" [algae produces aminos]

 

[SantaMonica]

Scrubbers compared to refugiums

If you are starting a new tank, then the obvious difference is that a scrubber gives you the option of not having a fuge at all because an upflow scrubber can be placed on top of, in, or behind, the display. There are other uses for a sump/fuge of course, but we'll only cover the filtration concerns here.

A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, along with the nutrients in the water and the nuisance algae in the display. However if this works for them, good.

But assuming you have to decide on either a sump/fuge or a scrubber (not both)...

o Filtration with algae is proportional photosynthesis, which is proportional to Light X Air Water Turbulence Flow X Attachment. Meaning, stronger light grows more algae; stronger air/water interface turbulence grows more algae; and stronger attachment lets more algae grow without it detaching and floating away. A scrubber is thus designed to maximize Light, Flow, and Attachment.

o The main problem with macros in a refugium is the self-shading that the macros do. Any part of the macro which is not directly in front of the light at any moment is not filtering. And any macro inside of a "ball" of macro (like chaeto) is self-shaded all the time. Only the surface macro that is directly in front of the light is doing any real filtering. A scrubber is designed to have all the algae in front of the light at all times. Rotating the macro does not solve the problem, because the time that the macro is rotated away from the light is time that the macro is not filtering. This is why it takes a much larger size of chaeto to do the same filtering as a scrubber.

o Self-flow-blocking is another problem of macros in a refugium, for the same reason as light-blocking. And the thicker the "ball" of macro, the worse the flow-blocking.

o Particle trapping is another result of a ball of macro. These particles need to cycle back around to feed the corals, but instead they get trapped in the macro and they rot, and in doing so they block even more flow and light.

o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the inverse square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae is proportional to the power of the light, because it's the photosynthesis that is doing the filtering.

o Rapid flow across the algae in a scrubber gives more delivery of nutrients, compared to the slow moving water in a fuge. Filtering is proportion to nutrient flow.

o The turbulence of water moving over the sections of algae in a scrubber help to remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have waves and bubbles). The interface between the air and water is what provides the most turbulence and boundary layer removal; there is no air/water interface in macros.

o Scrubbers do not let food particles settle like a refugium does; most particles flow right out of the scrubber.

o Scrubbers do not (if cleaned properly) release algal strands into display, like chaeto does.

o Scrubbers do not go sexual, like caulerpa can.

o Scrubbers do grow lots of pods; more than was previously thought, especially if not cleaned with freshwater.

o Scrubbers don't, obviously, provide a place for snails and crabs, etc.

However, if you already have a sump with an empty compartment, and you don't mind using all of it and putting a light over it, then maybe it's easier and cheaper to try macros first.

 

[SantaMonica]

Cleaning Off Slime On New Scrubbers

When scrubbers are new, they will almost always first develop a slimey first layer of growth. This is because diatoms and dino's, which make up most of the slime, are the quickest to be able to "colonize" a new surface, sort of like weeds in a new garden.

This slime layer will not get any thicker, however, because slime cannot attach well (it has no "roots") to the growth surfaces of the scrubber, and thus will get washed away when it gets thick, Also, it prevents green hair algae from attaching because of the slippery texture of the slime.

So when your scrubber is new, be sure to take it to the sink and use a toothbrush to clean all the slime off of the growth surfaces so you can see all white surfaces again. You could clean it while still in your tank if you don't mind the slime particles floating around, but most people would probably do better to take it to the sink (or outside; slime makes great fertilizer). Slime, especially when dark or black, is also an indicator that you can use more watts or hours of light.

Once you have cleaned off the slime for one or more growth periods, you should start seeing green hair algae take hold.