Backyard Aquaponics
A place to discuss aquaponics

Well I am finally starting to get the low pH under control but now I am having some kind of beige foam appear around the edge of the fish tank, according to my helper last time this happened we had a bunch of fish died off. What is causing this foam to form and is it's appearance warning of some water condition that is toxic to fish or was that a coincidence last time? In the past few days I have worked up the pH from 4.7 to 6.0 and cut the fish feeding schedule in half until proper pH is restored, I cannot imagine anything that I am doing could make the system more toxic then it was when I took over. Ammonia is still very high but that is nothing new, this system has been in the 3-4ppm range for months, or that is what the test is showing anyway.

If the system is constantly running at 3-4ppm then it's overstocked. A well balanced system should have an Amm level of 0.0ppm.

The foam is probably protein, it usually indicates high levels of organics in the water, which would make sense if the system is overstocked, especially if there is no form of mechanical filtration of the water.

There is mechanical filtration it is just not very good, not my design I am just trying to fix it. The pH was far too low for the ammonia to break down when I took over a few days ago that is why the ammonia is so high, I don't honestly think the system is overstocked. 12lbs of fish in a 600 gal system does not seem excessive, that and the nitrates have been near zero (0-5ppm) since the system came online. What could cause that protein foam to suddenly appear as I am raising the pH levels and does it indicate a threat to the fish if I continue bringing up the pH to normal levels?

What is the volume of bio-filtration, ie: wet gravel?

No gravel, shadecloth netting is the biofilter media, we might very well be overstocked for the amount of media we have but I won't know for sure until the pH is back in the range for the bacteria to start working again. The only thing I can tell you about the volume of our media is we have half a barrel of shade cloth netting loosely packed.

If the mechanical filtration is poor, then that netting is likely to be coated in solids and bio-filtration will also be compromised!

Raising the pH with ammonia in the system is risky, the higher the pH the more toxic the ammonia, at a critical point it could kill all the fish very suddenly.

I think it would make sense to sort out mechanical filtration first, clean out as much solids as you can, then install a biofilter with adequate amount of media for your amount of fish. Keep the bird-netting in the system, making sure to rinse off the solids regularly. Only then should you raise the pH any beyond 6, bit by bit, testing for ammonia nitrite and nitrate very carefully!

It sounds like a sketchy situation with your system, you will need to navigate your pH down a careful path between ammonia toxicity and biofiltration. First things first, get rid of the solids, provide biofilration and make sure there is plenty of aeration.

At a pH of 4.7 i'm surprised the fish didn't dissolve!

Yeah I kinna thought the same thing, the people that were running it before me obviously did not think it was nearly as dangerous as it stayed in the critical range for months prior to my involvement in the system, they did not even have anything to buffer the pH with I had to go out on my own and find some lime to treat the system with. I told my department head that the system is on life support until I could resolve the ammonia and pH issues because as you said the ammonia is more toxic at a higher pH but won't break down at a lower pH so I have been forced to raise it very gradually over the past week, finally got into the 6s today as well as made a few key modifications to the system. Shaded the fish tank, built a decoupled mineralazation tank, installed a makeshift mechanical filter, and added enough media material so the I should be able to keep the system alive while I remove the old material and clean it, just have to wait a few days for bacteria to colonize the new stuff. While I am waiting on the media to mature and ammonia to drop I have the fish on half rations, that is about the limits of my practical knowledge on how to bring a system back from the brink of meltdown, I have designed systems before, I have run systems before, but this is the first time I have had to bring one back from the dead.
The only part about all of this that really sucks is since I am the newest member of the team if something dies it is all my fault, but if I succeed then someone with seniority will take all the credit, that is just how life goes.

some people!.. sounds like a frustrating situation. I hope you get it to good health and producing mega vegetable growth, for your own satisfaction if nothing else!

good luck, keep us posted

Did the foaming start when you started raising the PH?

What are you using to raise the PH?

Is there any "smoke" swirling in the systems water & white "snow" anywhere?

It sounds like a bacterial bloom.But I've never seen or heard of foam.
Maybe now you've started to raise the PH,the bacteria can finally go to town & sort out the Ammonia,hence why it's happening now.

Yes the foam started when I started bringing the pH up, I am using ag lime to buffer the pH. No snow or smoke in the system, in fact since I got the pH back into the 6s (6.6 today) and added mechanical filtration it started looking really clean and clear other then the foam around the edges of the fish tank. I figured it was some kind of bacterial action causing it just did not know if it was the dangerous sort. Ammonia reading was 2ppm today, which is much better then the 8ppm reading I had last week, no I don't believe either of those numbers as 8ppm would have killed everything in the system, I think there is some mystery chemical interfering with the ammonia test, the only reason we do it is for a relative reading.

I was meant to say that about the test kit (is it reliable) but forgot while typing

The ammonia wouldn't have killed everything,the low PH would have prohibited the bacteria from doing its job.

If the Ammonia was high enough to kill everything,you probably wouldn't be able to measure it on the test kit.The liquid (test) will show a colour that's not on the pic chart.


Thanks goodness for that,that must be a relief.

Could you post a pic of the foam,just to see what it looks like.Out of interest please.

I wish I could post pics but it is inside a maximum security prison and I would have to get a media release from the highest levels in the agency to post any images. The reason I really want to save this system is that it is the pilot program for the state, poor management and a sub-par design has shifted interest more toward our hydro systems but I really want to keep aquaponics in the loop. Made some very important changes to the system; shaded the fish tank, increased the amount of biofilter media, built a decoupled mineralazation tank, built a basic mechanical solids separator and of course got the pH back into the productive range. I fear that is pretty much all I can do at the moment though as I have zero budget to work with and useful scraps are hard to find.
Our ammonia test kit reads up to 8ppm and our color reading was darker then the 8ppm on the card implying it was in fact off the charts. I am unaware of any fish that can live in that concentration of ammonia hence I think there is some other chemical reaction going on there. The foam looks very much like sea foam being a very light beige almost an off white in color, about an 1/8th inch deep and 1/2 wide all around the inside of the fish tank but not anywhere else in the system.

Ok I see.

Has the foam & Ammonia gone yet?

Yes the foam has vanished and the system is looking better. Ammonia is still reading very very high but as I said it cannot be that high in reality. Nitrites are reading at 0.00 nitrates are now reading 120ppm if anyone know a way that it is possible to have that kind of nitrite/nitrate profile and still have sky high ammonia I would love to hear about it. I am thinking either thermal degradation of the testing chemicals or an unknown substance in the water is causing the ammonia test to read that high, it has been that way for a long time.

Hi,

i had the same problem, and the problem was resolved by changing our food for a better quality, look also if the size of the fish food is correct, it can be caused by uneaten food.
watch for temperature swings coupled with uneaten food.