Backyard Aquaponics
A place to discuss aquaponics

Hi Scotty I have an update.
Algae has been completely removed water is crystal clear. I have been running air pumps 24/7 to keep up with o2 drops.

I do have another problem now. I recently check my levels and my nitrites and nitrates have skyrocketed and I lost 8 fish so far. I’m going to do a bug water change now. I’m not sure why I’m getting this constant cycle of algae then it’s gone the nitrite and nitrate spikes, then it starts again. It’s getting a bit frustrating.


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Sorry to hear about the fish deaths.

When the algae dies it becomes a source of protein which is then broken down into nitrites and nitrates. If your bio-filtration is not up for it then you get the spike of nitrites because the conversion to nitrate doesn't happen fast enough (the conversion to nitrate is done by the bacteria in your filter). If you don't have lots of plants to use the nitrates then they will build up. The nitrates aren't that big of a deal unless they are really really high but the nitrites are a problem. If you ever have to do this again, your goal should be to kill off the algae slow enough that your filtration can keep up so the nitrites stay low. You also could benefit from more plants in the grow beds to get the nitrates at reasonable levels - even though these aren't that bad for the fish, they provide a nutrient source for more algae growth (usually phosphorus plays a role in encouraging algae growth as well). I'm not sure what your levels are but you do want some nitrates for the plants you're trying to grow.

Nitrite poisoning is not a good thing to experience in AP. If you're still running with nitrites then you should salt the water to help protect the fishes gills against the nitrite ion (using sodium chloride or calcium chloride) (it's 1 part NaCl per thousand for the NaCl dose). The salt also helps the fish with building a slime coat and stress. Do what you can to improve your filtration or add more filtration so you don't run into this problem again.

Usually with nitrite poisoning you get fish deaths that happen a few at a time but over a period of weeks. These usually happen because the fish gills were damaged when the nitrite spike happened and it just takes awhile for the fish to die. Sometimes aerating the water will help keep some alive that might have died but usually the damage is already done and there's not much you can do to improve the outcome.

Yeah I had done some research and found that the algae along with some agitated solids buildup were the cause. I have salted the water (eyeballed the measurements) with the non iodine sea salt.

Since then I have cleaned out my solids filters, cleaned the DWC beds and did a partial water change. It seemed to have slowed it down but I’ll have readings on nitrates and trites soon.

Also I believe a lot of my plants may be suffering from nitrogen efficiency instead of iron (they seem to be very similar) what could I do to get some more nitrogen in the system?

Thank you as always.


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One other thing I did was take almost fully grown lettuce heads with roots and put them in the system. I also read up that having a variance of larger medium and small plants helps promote beneficial bacteria growth. So hopefully it helps suck up some extra nutrients as well


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Basically you want a lot of surface area for the bacteria. That surface area can be in the form of DWC channel walls, plant roots or media in media beds (and of course anything else they can find and glom onto that stays damp enough - bacteria need water).

It's possible that your problems are with nitrate deficiency, I won't rule it out - usually you'll get a general yellowing of the foliage with this, where with iron deficiency the yellowing is usually in the new growth (typically the top of the plant but it depends on how the plant grows - some send up new shoots from the base). The fact that you had a spike in nitrites makes me wonder about this and it seems a bit unlikely to be a nitrate deficiency since you did have measurable levels at one point. Nitrate deficiencies often come with a mix of other deficiencies because not enough food is going into the system.