Backyard Aquaponics
A place to discuss aquaponics

Hello all, I start my aquaponics system last year with feeder goldfishes. Recently the nitrate levels have increase dramatically (probably because the fishes grew really big) and if I don't do water changes weekly, the ph drops and the benefits bacteria dies off in my tank. I had this idea, fill my tank with green water. The green water will absorb the nitrates in the tank. I need green water anyway to feed my daphnias. But I have no experience with what green water will do to my aquaponics system. Will it absorb all the nutrients and left nothing for what I am planting? Will it clog the system and required more maintenance? Please if someone have experience using green water in their system, please advise me. Thanks.

I am just starting to do green water, but not in my aquaponics system. I am doing it in a small swimming pool to grow out some tilapia. So far the water parameters are perfect, but my pump gets clogged up a bit. Going to fix the clogging issue when I get home, my main pump is running fine, just my circulation pump tha is having trouble.

Shell grit will solve your pH issue. It should buffer it to around 7.6.

By green water are you talking about algae?

+1 for adding a pH buffer.

If your nitrates are "high" add more plants; if you don't have the space to do so, then simply reduce the feed to the fish. Less food means less ammonia will be generated, which down the line means less nitrates, so it's a reasonable course of action whether you add more plants or not. Goldfish can go for weeks without food, so you wont be stressing them.

If you allow the green algae suspended in water to thrive, they will suck excess nutrient from the water but they will also consume all of the available oxygen, which is extremely detrimental to your fish! You'll need to add extra aeration (which costs money and energy) to keep the system in a precarious balance. Suspended algae can also host waste solids, so you'll get a rapid build up of slimy gunk in your system which can clog pumps, pipes and envelope the GB media "suffocating" the beneficial bacteria.

KISS. pH buffer, less food, more plants.


Scott

Would you consider rehoming one or two of the fish? One thing to keep in mind is Goldfish dont have stomachs so they need to eat constantly.

Actually they do have a stomach. That is just a myth.
Same as 3 second memory, also a myth.

Huh... I guess I have fallen victim to myth spreading! I would still consider rehoming fish if you are having problems with nitrates.

I always wondered about that... thanks andrew

Bunson, I have algae issue I was going to leave to sort itself out. Thanks for tips on why it's bad. have to deal with it pronto. Ta

As far as I am aware goldfish do not have a stomach, they have an expandable foregut but that is not the same.

re: green water, I wouldn't intentionally grow it, as mentioned it is something that can be difficult to control and easily muck up a system. Increase plant uptake or reduce bioload to level things out. If you have enough light hitting the tank to grow greenwater algae then you could throw something like anacharis/elodea or some sort of hygrophila in there. My goldfish pond has both anacharis and hygro sp. tiger and the goldies don't mess with it, at least not enough to keep me from having to remove handfuls each season to make space.