What's in my fish water

[Jeff S]

I have a 600 gallon system and have nitrates as high as the API test will register. Ammonia is .25 and pH is around 6. The dissolved solids are 2600ppm. I adjust pH with potassium hydroxide and garden lime. I also add the occasional Epsom salt and iron chelate. My veggies grow ok but nothing special. I am going to try a Kratky hydroponic setup and the fertilizer I'm going to use says to add equal amounts of Calcium Nitrate. My question is could I possibly use my fish water and forgo the calcium nitrate? I probably should have the water tested but don't know where to get that done around here.

[Frank Buffone]

Hi Jeff,

I am surprised no one has replied to your question as yet. Without knowing anything about your system other than what you offered, I would say, 1. you have too many fish in your tank producing more waste than your plants can remove. 2. The obvious next response is that you don't have enough plants utilizing the nitrates in your system. 3. Ammonia present means there isn't enough bacteria to convert it to nitrites which means too many fish. How long has the system been running? Is it exposed to rain water? How much are you feeding your fish? Have you ever done a water change? Chemical adjustment to your system doesn't do the plants or the fish any good. I just makes it fluctuate wildly without addressing the real problem.

Good Luck, Frank B.

[Jeff S]

 
Yes I definitely am way overstocked but my question was concerning how to utilize the high nitrate water. I was thinking of using it in a Kratky DWC bed and just replacing the water in the fish tank since there's not enough room in my greenhouse to build more filtration grow beds. Since my original post I've had 2 episodes where I lost all my sump water so Ive had to add about 300 gallons to the system so my #s all have come down.

 

[Frank Buffone]

Conserving water use is an integral part of this growing system. Constantly removing and replacing water kind of defeats the purpose. Are you growing fish that can be eaten? If not then remove some. If your system is in a greenhouse , you will have to do water changes regularly about once a month. I lose a lot due to evaporation but the rain generally keeps up with the loss. Balance your environment and there won't be a problem with too many nitrates. What will you do with the nitrate concentrated water in the winter when you don't need it?

[Jeff S]

I'm growing Tilapia and there are a lot of them. The water never needs to be replaced even though it's in a greenhouse except for evaporation but since I have to water dirt gardens as well it's not like I'm wasting the water if I use it for that purpose. The nitrate level will stay low enough over the winter if I have used the tank water in the fall for garden water. Conserving water or knowing how to do it is useful but only if you have a water crisis. From my early years of aquaponics I expended a lot of energy trying to learn it as if I were a prepper. While I like the concept and have fun making things work it would have been much easier to get in to by just buying what I needed and cutting back after I knew what I was doing.
 
Frank Buffone said:

Conserving water use is an integral part of this growing system. Constantly removing and replacing water kind of defeats the purpose. Are you growing fish that can be eaten? If not then remove some. If your system is in a greenhouse , you will have to do water changes regularly about once a month. I lose a lot due to evaporation but the rain generally keeps up with the loss. Balance your environment and there won't be a problem with too many nitrates. What will you do with the nitrate concentrated water in the winter when you don't need it?

[Tom Oliphant]

Since the end of cycling for my 600 gallon system I have always had Nitrates over 160 ppm. Nitrates are good. If you are worried, plant more plants. The system should balance out and not require a lot of tweeking. I am a pilot. If you steer by the attitude indicator and compass you will crash because there is a built-in delay between reality and the readings. They are just supplemental data in support of what you see around you. I think this is why The Aquaponics Source has Rules-of-Thumb and not Commandments.

TVO >:)