Can Biopellets REALLY cause Cyano growth in a low nutrient environment?

[GroktheCube]

My tank specifics, before I get into my post:
-120G mixed reef, 40 breeder sump, will be 1 year old in January
-Aquamaxx EM-300 Skimmer, Aquamaxx Biopellet reactor with Warner Marine pellets, TLF reactor with BRS ROX carbon (changed ~monthly)
-2x BuildmyLED 48", 72 watt LED strips, ATI Sunpower 4 x 54watt
-Tunze 6095, 6105, 6055, 6065, with all controllable pumps hooked up to Tunze wave controller. 6105 and 6095 are positioned opposing each other, switch from one to the other every 6 hours.
-Elos ATO
-BRS peristaltic dosing pumps for alk and cal.
-Apex to run all this stuff.

Chemistry and such:
-Temp 78*F
-Salinity: 35ppt
-pH: Low of ~8.05 at night, high of just under 8.3 during day
-Alk: 7.5 dKH (Hanna a few times a week, Red Sea once a week)
-Cal: 450
-Mag: 1350
-Nitrate: 0.00 (Red Sea)
-Phosphate: ~0.02 (Hanna when I feel like it/remember to, Red Sea if I think Hanna is lying)

Junk I put in the water:
-3ml of KZ Aminos daily
-~2 cubes of frozen per day for fish prepared with selcon and zoe, juice goes into tank as well
-A few pinches of NLS and/or blue zoo pellets here and there
-Reef Chilli
-ESV freeze dried phyto (more for the fish than the inverts, they love it!)
-Every other night or so corals get target fed 2-3 cubes of frozen, mixed with reef chilli, Zoe, and Selcon.

WC/Top off water source:
-150GPD RO/DI with 2 mech filter, 3 carbon, and 3 DI stages. Not because I think all those extra stages make it work better, but because I can go longer between changing them.
-Stored is 32G Food Grade Rubbermaids.
-ESV B-Ionic salt.
-PanWorld pump to get it all upstairs to where the tank is.

Onto the post

I ask about BioPellets and Cyano because I have had BioPellets running for about 6 months now on my 120 mixed reef, and they seem to have done a good job of helping me keep dissolved inorganic nutrient levels low despite heavy feeding. As of this morning, nitrates are undetectable, PO4 is .02.

However, over the past months or so, there has been some red cyano growing in a few places in my tank. Usually in small quantities, and I always remove it within a day or two if nothing eats it, but it's a little annoying. The only other algae I have growing in the tank is coraline and some macro that I allow to grow on the rocks in spots where I don't currently have any corals placed to "fill in" the empty space, and a few bits of valiona (which tends to be rapidly overgrown with coraline, making "purple bubbles") here and there. I have very little film algae that grows. Absolutely none that is visible on the rocks, and I only need to scrape the glass about once a week.

Over the past week, cyano growth seems to have gotten worse, with a considerable area of rock in one of the lower flow and lower light part of the tank being covered. I actually haven't bothered removing it yet, because I'm hoping it will smother out a few aiptasia back there, but I plan to within the next couple days.

Could this be connected to biopellet use? I use an AquaMaxx BP reactor, and I've plumbed the output into my AquaMaxx EM 300 skimmer by cutting a notch in a PVC tee to allow just enough room for the venturi line, and using a simple silicone O-Ring to hold it on the intake volute. I left about 2" of PVC on past the T to make sure all the water inside the T would always be flowing into the skimmer.

Another odd phenomenon that I've noticed over the past month is that alk demand seems to be exceeding cal demand. I'm currently dosing (via BRS dosing pumps controlled by Apex) ~20ml of ESV B-Ionic 2 part to maintain 7.5dKH, but only ~15ml to keep cal at 450.

I know this post is a bit rambling, but I'm rather puzzled. There weren't any major changes to my husbandry around the time the cyano started showing its head, and all of the chemical parameters I measure seem to be exactly where they should be.

If it was the BioPellets, it seems odd that it would take 5 months for the problem to start showing itself. If it was something else, I have no clue WTH it could have been.

I'm tempted to take the BPs offline to see if the Cyano goes away, but I may need to start doing something else for nutrient export at that point to keep up my heavy feeding.

 

[rgfast]

I can't say for sure carbon dosing caused cyano in my system but I had the same thing happen to me about a year ago. I think over time I've tried about every trick of week product ZeoVit, Bio-pettets and so on and finnally just got fed up. That being said I removed every reactor from my system and was ready to just break it down and within a few months things started to look better. Long story short now days I run a skimmer that is rated double my system volume along with 25micon socks and my system looks better than it ever has as well as being rock solid stable. I'm now happy with my system, just running old school and no frills and if I see my po4 start to rize I just run a little gfo.

 

[GroktheCube]

Thanks for the input. I've read a fair amount of people that have reported similar things. I'm trying to figure out if there's a way to combat it without taking the BPs offline, as I think they've been tremendously helpful overall.

I'm going to try very aggressive GFO and/or LaCl use in an attempt to push phosphate levels to as close to zero as possible, slightly decrease flow through the BP reactor, and increasing the frequency of WCs. If I feel like going really crazy, I may raise the temperature by a degree or two just to see if that has an effect either way.

 

[jimmcwibb]

You say you feed heavily and rely on the pellets to remove the excess nutrients. But the cyano will compete with the pellets for those nutrients, and as the mass of cyano increases they will compete more effectively. They also have an advantage in that they are able to fix nitrogen to a bioavailable form.

If you are going to decrease the flow through the reactor, this might result in two outcomes. If the carbon is the cause of the cyano, you should see a slow down in cyano growth. If not, the cyano growth will increase as the pellets remove nutrients at a slower rate.

Ultimately I think the best course of action would be to reduce feeding.

Edit: aggressive use of GFO or LaCl to reduce phosphate could mask the result of reducing flow through the reactor. I would only change one thing at a time else you will never know what worked.

 

[Timber77]

Yes carbon dosing can feed cyano in a low nutrient environment. I don't know anything about your skimmer but if you dose carbon you need a much stronger skimmer than you would normally run. I would suggest taking the biopellet reactor offline for a couple weeks and see if thats your problem. Also in case the cause is not the bio pellets, Test your ro/di source water, and any possible source of phosphate introduction. Phosphates feed cyano.

 

[sh0ck]

I would expect to be little more complex.
I have no deep knowledge of this, but if u ask - what can grow in tank with higher NO3 and PO4? any algae
But for any leather/algae etc u still need NO3 to create the body mass.
So what will consume P without big amounts of NO3?
I would start with additional NO3 dosing and see how it will react.

Also are u rinsing frozen food well before throwing into tank? As there is a lot of PO4 on input side which can be avoided.

 

[jimmcwibb]

Also, I don't like this bandying about of the term "low nutrient environment". If Grokthecube has algae growing, the environment is not low nutrient. The test kits might give low results but this is only a spot measure and not a measure of the flux of nutrients through the system. Nutrients in (feeding) = nutrients out (algae + biopellets). The only reason the test kits read low is because the algae and biopellets are taking up the nutrients very quickly.

 

[Duna_]

Phosphates feed cyano.

That's the point ...

You surely have a lot of nitrate and phosphate in your tank, due to heavy feeding. But it's mostly consumed. Biopellets take care of the nitrate, lowering it to zero. But who takes care of the phosphate in a zero nitrate situation? Cyano does, because it can fix nitrogen gas from the water.

The fact that you have 0 nitrate and measurable phosphate confirms this, the phosphate is also been consumed, but it's still present and available at enough quantity.

You need to compete with the cyano. Macroalgae like chaeto love phosphate, but they also need nitrate.
Frozen food and also dried food has a lot of phophate. A lot more that we normally thought. A single cube of a low phosphate frozen food can add 0,04 of organic phosphate to a 100 gallon tank (in every feeding).


I've had Biopellets for 7 months, but I also have chaeto growing very well in the fuge. I feed heavily, no pale corals, and no problem of cyano. Nitrate and phosphate are at 0.


Byess

 

[GroktheCube]

Also, I don't like this bandying about of the term "low nutrient environment". If Grokthecube has algae growing, the environment is not low nutrient. The test kits might give low results but this is only a spot measure and not a measure of the flux of nutrients through the system. Nutrients in (feeding) = nutrients out (algae + biopellets). The only reason the test kits read low is because the algae and biopellets are taking up the nutrients very quickly.

This is definitely a fair criticism. Generally, when people refer to "low nutrient", they're speaking specifically about dissolved inorganic N and P, because it is this measure that is often used to describe coral reefs as "low nutrient".

However, on coral reefs, the quantity of nutrients available in terms of food absolutely dwarfs what we can realistically provide in our tanks.

The first thing I will try to do is drive phosphate as close to unreadable as I can. I gather that many people run GFO with BPs anyway. If at this point I'm still seeing much in the way of cyano, I'll reduce BP flow.

 

[rgfast]

I'm sorry if I'm mistaken here but cyano is not an algea as everyone here's seems to be calling it, it's a bactira and the oldest form of life on the planent. I think with to much carbon dosing it can out compete all other bac. and become mono source. I'm no expert just my opion, want it gone? three days lights out.

 

[GroktheCube]

I'm sorry if I'm mistaken here but cyano is not an algea as everyone here's seems to be calling it, it's a bactira and the oldest form of life on the planent. I think with to much carbon dosing it can out compete all other bac. and become mono source. I'm no expert just my opion, want it gone? three days lights out.

It is a prokaryotic bacteria, yes. People often refer to or treat it as algae since it appears similar at a macroscopic level, and uses photosynthesis.

I know that "lights out" can kill it, but I'm trying to see how low N and P levels can get while still allowing its survival.

Hanna ULR is now reading 3-7ppb of P, so 9 - 21 ppb of PO4. Pretty wide possible range, it annoys me that measurements vary so much test to test with this thing.

 

[chercm]

Do u still run bio pellets at the moment ?

I can't say for sure carbon dosing caused cyano in my system but I had the same thing happen to me about a year ago. I think over time I've tried about every trick of week product ZeoVit, Bio-pettets and so on and finnally just got fed up. That being said I removed every reactor from my system and was ready to just break it down and within a few months things started to look better. Long story short now days I run a skimmer that is rated double my system volume along with 25micon socks and my system looks better than it ever has as well as being rock solid stable. I'm now happy with my system, just running old school and no frills and if I see my po4 start to rize I just run a little gfo.

 

[bigbpro916]

I dont believe in bio-pellets....good skimmer, adding 2-part, water changes, and a good light schedule!!!

 

[rgfast]

I dont believe in bio-pellets....good skimmer, adding 2-part, water changes, and a good light schedule!!!

+1 my system seems much happier without the carbon dosing

 

[sh0ck]

Well, u dont dose carbon just cause u can.
But with too much overfeeding or fish, there are not many choices.

 

[jimmcwibb]

Hanna ULR is now reading 3-7ppb of P, so 9 - 21 ppb of PO4. Pretty wide possible range, it annoys me that measurements vary so much test to test with this thing.

I work with ICP-MS, ICP-AES and XRF at work... machines which cost millions... we put a lot of effort into measuring things at the ppb level. Sure we're looking to get accuracy within 5% but I find it amazing that a simple test kit could even approach the ppb level at home.

 

[GroktheCube]

I think its because my microfiber cloth that I use for cleaning the test tubes was dirty. Consistently 3-4 ppb of P now, so 9-12 of PO4.

Yeah, it is pretty cool that a hundred dollar green egg can deliver that degree of precision with reasonable accuracy.

 

[Timber77]

No aquarium grade test kits can measure bound phosphates- its just not possible without a real lab. Phosphates are feeding the cyano. If you have cyano really don't use the test kit your just gonna confuse yourself. The test kit is not accurate, your eyes seeing cyano is accurate. 4 year degree in organic chemistry and plenty of time using gc mass spectrometers, as well as 25 years of cyano free tanks are my resume.

 

[simonh]

I think that most aquariums have ample phosphate available for things to grow (cyano, diatoms, algae, corals) as we are constantly adding it with food. So you don't need some big pool of it sat around, you are adding it everyday!

What may determine the microflora is whether they are limited by another nutrient. For example, diatom growth may be limited in a reef tank due to the low levels of silica rather than nitrate or phosphate. Likewise, bio-available iron may be a limiting nutrient for algae in some tanks. In these tanks I think it is entirely possible that another organism such as cyano may get a foot hold where it is able establish a population due to use of N2 gas, P from the tank, and maybe the addition of carbon sources from elsewhere.

 

[Kolognekoral]

Duna made a good explanation of what happens in many tanks. If there is some source of phosphate, cyanobacteria will attempt to utilize it.(and don't forget the Redfield Ratio) With their ability to fix N2 direct from the water they are at an advantage. Many tanks do have deposits containing PO4,(CaPO4 and similar) which may be set free either due to the increased general tank metabolism driven by the bacteria or simply be a local phaemonenum due to degrading organics.

Carbon doing increases the tank metabolism many fold, which may be why we see some tanks developing algal/cyano issues and then settling in. The tank is seeking a new stability.

I've been working with carbon dosing for over 10 years and am currently using pellets. All cyano issues that turned up went away of their own accord. Patience (and I don't mean 7 days!) is key to all marine systems.

To answer the original question, do pellets feed cyanobacteria, the answer is NO! You have fed them by constantly adding PO4 to the system via food and the bacteria promoted by the pellets are correcting the issue as best they can. Essentially, one has pushed the Redfield Ratio and you have an NO3 deficiency with excess PO4, which is constantly being added by food, is getting the overhand.

Exactly why one ends up with excess PO4 can be for various reasons. The fish, type of foods, general husbandry, etc. this is why it is so difficult to pinpoint for any given system. I have experiemented with adding ammonia (nitrates) to balance PO4 with success. Others found it difficult to impossible. Clearly our tanks are often very different.