Algae Scrubber Basics

[srusso]

Hey srusso,
I notice the top of your screen is very clean. Is that just because it's all in the slotted pipe or are you doing something to block the light there?

I left the top of the screen without being roughed up. A side from that it's probably b/c my new scrubber is only about 1 week old. As it ages it will grow more at the top.

It's also growing where the light is most intense.

 

[Robert Patterso]

I just wanted to comment on the center-lamp idea. When you take a 2-screen system and put lamps in between the screens, so you have lamps-screen-lamps-screen-lamps, the center lamps have about 1/4 of the effectiveness. The reason is that #1 you are splitting the lamps between 2 screens, and #2 you lose all the light power that is not directed/reflected one way or the other. Since no one makes a reflector that can effectively take a linear light source and direct 50% of it one way and 50% the other way, you end up with a bare lamp in between the screens. So it sounds great on paper because it saves real estate but to get the effectiveness of 1 reflected T5HO on the outside, you would need 3 or 4 lamps stacked up next to each other on the inside.

This is why I am not a fan of the center-lamp design. You just can't squeeze any more lumens out of a lamp. You are way better off going with 48" lamps, or just making 2 24" units. If you made a 4-4-4 unit, you would be better off making two 3-3 units, because you can reflect all the lights and maximize the power to the screen.

Also T5HO fixtures are 24" long, but the portion of the lamp that is actually illuminated is more like 20", so having much wider than a 22" screen doesn't do a whole lot. If you use T5HO waterproof endcaps, you end up with 19-7/8" exposed lamp.

Also like srusso said, you have a maximum lamp spacing of about 3 or maybe 4 inches. So 3 lamps on a side means a 12" x 22" screen, two of those means you have about 24x22 scrubbing power or about 525 gallons of filtering capacity. Having your lamp spacing a little wider than 3" will decrease that a little, but using T5HO you're ahead of the game, so that would effectively filter a 500 gallon fully stocked tank. So if you have 900 gallons and it's half stocked (or only moderately fed) that will probably work well.

Hope that helps

It is a lfs display fish system. I will have a total of 16 lights. 5 on outside, 6 in the middle and 5. The 5 on the outsides(or total of 10 outside) will have individual reflectors. The 6 in the middle will not have reflectors. I intend to space the screens as close to the lights as possible and still have splash guards.. If I could get 36" lamps I would but 48" is to long for this application.

 

[Floyd R Turbo]

It is a lfs display fish system. I will have a total of 16 lights. 5 on outside, 6 in the middle and 5. The 5 on the outsides(or total of 10 outside) will have individual reflectors. The 6 in the middle will not have reflectors. I intend to space the screens as close to the lights as possible and still have splash guards.. If I could get 36" lamps I would but 48" is to long for this application.

I know, i read that post also. I'm tying to save you a little $ on lamps and fixtures. You will get the same amount of power if not more by doing 2 3-3 systems than you will a 5-6-5 system. The 6 lamps in the middle will be like 1/4 of a lamp each to each side. The remaining 1/2 of the lamp power is completely lost. So it will be like the equivalent of 1-1/2 lamps going each direction. Thus you have 2 screens with 6-1/2 lamp power, maybe 7 at the most.

If you're going to squeeze 5 lamps across 24", that's 4-5" per lamp. You're better off spacing 6 lamps 4 inches apart, 3 on each side, of a 12" tall 24" wide screen, and doing 2 of them. If you're dead set on a 24" tall screen (and you have the space to do that) then do them vertically and do 6 on one side and 6 on the other, and get good reflectors.

 

[Robert Patterso]

I know, i read that post also. I'm tying to save you a little $ on lamps and fixtures. You will get the same amount of power if not more by doing 2 3-3 systems than you will a 5-6-5 system. The 6 lamps in the middle will be like 1/4 of a lamp each to each side. The remaining 1/2 of the lamp power is completely lost. So it will be like the equivalent of 1-1/2 lamps going each direction. Thus you have 2 screens with 6-1/2 lamp power, maybe 7 at the most.

If you're going to squeeze 5 lamps across 24", that's 4-5" per lamp. You're better off spacing 6 lamps 4 inches apart, 3 on each side, of a 12" tall 24" wide screen, and doing 2 of them. If you're dead set on a 24" tall screen (and you have the space to do that) then do them vertically and do 6 on one side and 6 on the other, and get good reflectors.

Ok sorry for asking dumb questions here. So your saying use 3 reflected lights per side for a total of 6 lights per screen, right? I am trying to cover the total gallons in the system that was why I was going with the 24x24 screens. We are wanting to make sure the scrubber will handle the load no matter what we throw at it. I will have a total of 16 lights, so should I put reflectors on all of them? Say 4 per side per screen?

 

[Robert Patterso]

By the way, heighth wise I have all the room I need. Probably 16 ft above the sump if that helps any.

 

[Floyd R Turbo]

Oh, in that case!!

So you want to do 2 sets of 24x24 screens, which would put you over 1000 gallons of capacity, right?

If that's the case, then 16 x 24W (24" T5HO) = 384 W and you're pretty underpowered. Realistically, you're probably not going to feed them 100 cubes of food a day though, are you? Because that's what a scrubber that size can technically handle.

That's why I'm thinking that your scrubber is a special case where you can undersize it, and make sure you have plenty of flow and light.

 

[Robert Patterso]

Oh no way will it ever see that much food, ever. But yes I am trying to cover right at 960 gallons. Of course the fish come and go, get sold. So the load is never the same. Up one day and down the next. We are trying to go to a more natural way of filtration. Each display tank is a 55 gallon tank except for 1 and its a 100 gal. I think. So while I am trying to filter that many gallons I don't think I have the room horizontially. The area I have to work with in the sump is 36x24. But I have all the vertical room I need. But from what I understand, and correct me if I'm wrong, horizontal works better than vertical. I've already ordered the bulbs so I am kinda stuck with it. I can always order more if need be, just need to come up with more end caps.

As far as flow goes, that's not a problem. The owner told me to grab whatever pump/pumps I need to get the flow I need

 

[Floyd R Turbo]

Are you going to do an enclosed acrylic box? I don't remember you mentioning anything except for lighting and screen dimensions.

 

[Robert Patterso]

Are you going to do an enclosed acrylic box? I don't remember you mentioning anything except for lighting and screen dimensions.

No acrylic box, at least not right now. Goin to build a frame out of steel, all welded and powder coated. Once we get this up and running then we are going to plan and build one for the store's display sps/mixed reef. That one probably will be either acrylic or glass which will be on display right next to the tank itself. Hopefully to draw attention from the customers. Once we get the bugs worked out of the ones in the store we want to try and build and sell custom set ups to the customer. I believe this type of filtration system is the better way to go and cheaper in the long run. Don't need all the bells and whistles, skimmers and such. I will be building a better one for my personal tank here at home to hopefully take my skimmer and refugium off line.

 

[6Speed]

some more ideas I might work with. I like the idea of mounting some hangers to the inside glass of the sump. Heck I could even make some hangers that hang onto the top edge of the sump. Another idea I like, if I choose not to feed the thing from the overflow, is to utilize the return pump and a t-fitting plus valve.

The overflow idea I think is great bc 100% of the nutrient rich water will pass over the scrubber before going anywhere else. The con of that setup would be if the screen or pipe got clogged and the overflow wasn't able to deliver the same amount of water that the pump was sending into the tank. Then we'd have a big mess!

 

[srusso]

...and correct me if I'm wrong, horizontal works better than vertical.

That is incorrect... :spin3: :hmm3:

 

[srusso]

The con of that setup would be if the screen or pipe got clogged and the overflow wasn't able to deliver the same amount of water that the pump was sending into the tank. Then we'd have a big mess!

Feeling like I have answered the question a million times, so if it sounds a little short thats why... but in short... A properly maintained scrubber can not clog on its own accord... The reasons have been posted on this thread a bunch of times. "In shorter" algae loses to the water pressure.

Nice single sided screen. Let us know how it works out for you. Thanks :wave:

 

[Floyd R Turbo]

That is incorrect... :spin3: :hmm3:

I think he was saying that a wider, shorter screen is better than a taller, narrower screen.

 

[Floyd R Turbo]

I think that's a copy/paste of someone else's build, right? It was that guy that used to have that really long and narrow DIY acrylic tank that was totally awesome, then he sold it and made a Nano and this is his sump. Is that right? I think it was a TOTM at one point (the long tank)

 

[srusso]

I think he was saying that a wider, shorter screen is better than a taller, narrower screen.

Yeah after reading the line a second time... you are right.

 

[6Speed]

I think that's a copy/paste of someone else's build, right? It was that guy that used to have that really long and narrow DIY acrylic tank that was totally awesome, then he sold it and made a Nano and this is his sump. Is that right? I think it was a TOTM at one point (the long tank)

the pics I posted? yes those photos are from Calvin's thread in the nano forum. I really like his design.

edit: sorry, I see you quoted the pics too. I was reading the topic on my phone when I originally replied to your quote and for some reason the images didn't show up.

 

[6Speed]

Feeling like I have answered the question a million times, so if it sounds a little short thats why... but in short... A properly maintained scrubber can not clog on its own accord... The reasons have been posted on this thread a bunch of times. "In shorter" algae loses to the water pressure.

Nice single sided screen. Let us know how it works out for you. Thanks :wave:

That's actually not mine. I was posting it bc I liked his design and wanted to incorporate some of the elements into mine.

Regarding clogging. You're telling me there is no chance that algae will grow on the screen close to where the screen meets the pipe? There is no chance of that algae growing thick enough to slow down the flow of the water as it exits the pipe?

I'm not concerned of algae growing in the pipe...just the stuff that may grow right up to the edge of the pipe.

I'm sorry if you've answered this before, but the thread is very long and I must have missed it.

 

[Floyd R Turbo]

I'm going to cover solution to this in detail in my Summary Part #2, but here's a sneak peek at my explanation of why it's not really a concern:

Slot pipe clog prevention

This issue is brought up on a pretty regular basis. Obviously, no one wants an overflow pipe to clog and overflow their tank. Most people take precautions to prevent livestock from entering the overflow pipe, such as an intake screen. In the case of the scrubber, they’re worried about the algae growing thick enough to stop flow at the point where the screen and pipe slot meet.

Almost without exception, this question is posed by someone who studies the design, but has never actually built or operated a scrubber for any length of time. I’m not trying to belittle anyone posing the question by saying that, rather just making the point that if you run a properly built scrubber, you’ll understand that this is really not a concern. Here’s why:

If you properly build and maintain a scrubber, there is virtually no chance that algae will grow thick enough to block the slot. I’m not saying that algae will not grow at the junction point of the slot and screen, it most certainly will to a certain extent. The water on the screen below the slot will get partially diverted over the top of the algae mat, as water takes the path of least resistance. As you approach the slot, the flow area is restricted to the narrow space between the pipe slot and the screen. This creates an area of flow pressure under which algae cannot grow to any significant thickness without succumbing to the pressure of the flow and releasing from the (smooth) screening material. Proper cleaning of the slot and the smooth portion of the screen during weekly screen cleanings virtually eliminates any chance of the slot clogging.

As for the interior of the overflow pipe and slot pipe, these can be clogged by variety of means. The most obvious of example is a snail, anemone, or other tank mate that makes its way down the pipe. This is a potential problem for any overflow pipe, but adding a slotted pipe with a cap on the end just makes some people nervous, because there’s no place for that obstruction to exit the overflow pipe. Fortunately, this is only a problem when you insert the screen too far into the slot pipe. If you only insert the screen far enough that is extends about 1/8” to ¼” above the inside of the pipe, then anything that makes it all the way through the plumbing to the slot pipe will get pushed to the end of the pipe by water pressure, and should only partially block the flow, and only at the end of the screen, if at all.

If you insert the screen all the way into the slot until it contacts the inside of the pipe, the obstruction could form at the beginning of the slot tube, and could substantially or completely block the water flow. However, this is perfectly fine as long as the inlet to your overflow pipe has a strainer on it that would prevent anything from entering the pipe.

I don't know if there is any advantage to full insertion vs. minimal insertion. Inserting the screen further into the slot pipe may even the flow out a bit, but I haven't noticed any glaring issues with the way I do it. This is why I recommend inserting the screen such that it protrudes no further than ¼” into the interior of the slot pipe.

With all that said, if you’re still concerned about the issue, and don’t want to take any chances at all (and you would be hard pressed to find someone to blame you), then there are a few techniques that can be implemented that will reduce or completely eliminate the chance of a blockage of the slot pipe causing your tank to overflow. Notice that I only mention a blockage of the slot pipe. This is because a blockage of the overflow plumbing before] the slot pipe is a totally different issue, but some of the solutions below will apply to both.

The 'few techniques' will be covered in part 2 summary.

I'll follow that with my personal note that after looking at hundreds of scrubber builds, threads, etc, I haven't seen one person say that algae grew into their slot tube clogged and overflowed their DT.

I'm not saying that it couldn't happen, but if it did, it would probably be directly attributable to the slot not being wide enough and pinching the screen, which would result in not enough flow from day one.

 

[6Speed]

Thank you for putting my mind at ease Floyd! That is certainly good news!

I'm curious to know what tool people are using to cut the slot into the pipe? I am guessing a dremel is a popular method.

I'm also curious to know the different methods of holding the screen in the pipe. One way I considered was to cut the very edge of the screen (that sits inside the pipe) slightly wider than the rest of the screen so that it could hang on each end of the slot. Is this common or ok way to do it?

 

[redneckgearhead]

I use removable zip ties, Ive seen some use shower curtain hoops, If you have time to look back through the pics in this thread you can see several different ways to hold the screen in.