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Hello Everyone

I have very high nitrates (40 ppm) in the tap water that goes into my tilapia tank (110 gallons). Could someone tell me what would be acceptable nitrate level for tilapia. I am thinking of investing in a reverse osmosis unit with deionizer to take care of some of the high nitrates. 

Thanks for the help

Vishnu

System details

Ammonia: 0.25

Nitrite: 0.25

Nitrate: 40 ppm

Ph: 7.6

Fish Tank size: 110 gallons

Grow Bed: 8'x2'x10"

Age: 3 weeks

# of Tilapia: 10 fish 2-3" across

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In my research on the subject I have read studies that say high nitrate levels can effect the rate of growth in fish.  A level of 40 ppm is pretty high coming out of the tap and has health risks for humans, pets and especially infants. Once your bacteria begin to create more nitrates on top of that you could get into the kind of toxicity that will have an effect on the fish. Do you live in an agricultural area?

I live up on a hill so the water comes from wells up on the here. But I am not sure if the water table is connected to everything else on the island because just up hill from the wells were large Dole pineapple plantations that used a LOT of pesticides over the decades and I heard that it has contaminated the water table in the general area. I guess now I have to buy an RODI unit to make things better for me and the fish. I might get another test kit to make sure the readings are the same just in case the one I have is bad. Thanks again for the help.

Vishnu

It could be fertilizer runoff or sewage.  I hope that's not your drinking water.  If it is, maybe you should filter it. 

Regarding your aquaponics, plant lots of plants and they should take care of it.  I can barely detect nitrates in my system. 

Have your water professionally tested, it is worth it for your safety and the safety of your fish friends.

moonyguy said:

I live up on a hill so the water comes from wells up on the here. But I am not sure if the water table is connected to everything else on the island because just up hill from the wells were large Dole pineapple plantations that used a LOT of pesticides over the decades and I heard that it has contaminated the water table in the general area. I guess now I have to buy an RODI unit to make things better for me and the fish. I might get another test kit to make sure the readings are the same just in case the one I have is bad. Thanks again for the help.

Vishnu

I wouldn't worry much about the aquaponics end. The nitrates will be used up pretty fast. I did just read an artcle about how RO could limit needed micronutrients for the bacteria, though. So I would look into that before for you decide to go that route.

A tap water nitrate reading of 40 is high and you could probably use that water to feed your plants without having fish.  Definitely worth it to get some professional water tests done to find out if it is safe to be using that water yourself.

Sorry, a little late to the discussion. I live directly below you, if fact we share the same water source. I'm showing 5+ ppm for nitrates from my tap water. Go to boardofwatersupply.com and you can put in your address to get the water report and the wells that are used for your area. Maximum allowable is 10 ppm according to the report.  They are showing a range of 2.8 - 3.4 ppm in their report.

I hope this helps

just to say -  do not drink ro water, it isnt good for you, it can actively absorb things from your body and is often used in short term cleansing or de-tox but long term use can cause serious health consequences including rapid loss of elecrolytes such as potassium sodium etc and minerals that you need in your body, can be especially dangerous for infants.

lots of people have in the past talked of health benefits from this and it can help with short term removal of toxins for detox but long term can cause more harm than good.



moonyguy said:

I live up on a hill so the water comes from wells up on the here. But I am not sure if the water table is connected to everything else on the island because just up hill from the wells were large Dole pineapple plantations that used a LOT of pesticides over the decades and I heard that it has contaminated the water table in the general area. I guess now I have to buy an RODI unit to make things better for me and the fish. I might get another test kit to make sure the readings are the same just in case the one I have is bad. Thanks again for the help.

Vishnu

Jonathan, can you link to any studies that point to the effect of nitrate on fish @40ppm...

 

This issue came up years ago on the Australian forums, and at the time when I was doing my aquaculture studies...

 

And I could not find any research that suggested anything below a reading of 450ppm.. as toxic, or detremental to fish... and that was for bluegill...

 

I have often seen figures of 40-60ppm suggested on aquaria sites.... but these seem to relate to specific sensitive marine ornamentals... and corals... not freshwater fish...

 

Certainly those levels are a concern with regard to drinking water...

 


 
Jonathan Kadish said:

In my research on the subject I have read studies that say high nitrate levels can effect the rate of growth in fish.  A level of 40 ppm is pretty high coming out of the tap and has health risks for humans, pets and especially infants. Once your bacteria begin to create more nitrates on top of that you could get into the kind of toxicity that will have an effect on the fish. Do you live in an agricultural area?

I wasn't really suggesting 40 is too high for the fish, just for humans according to the EPA. I would definitely defer to you on the subject of fish Rupert, my main concern was that Vishnu might have unsafe water for himself.

RupertofOZ said:

Jonathan, can you link to any studies that point to the effect of nitrate on fish @40ppm...

 

This issue came up years ago on the Australian forums, and at the time when I was doing my aquaculture studies...

 

And I could not find any research that suggested anything below a reading of 450ppm.. as toxic, or detremental to fish... and that was for bluegill...

 

I have often seen figures of 40-60ppm suggested on aquaria sites.... but these seem to relate to specific sensitive marine ornamentals... and corals... not freshwater fish...

 

Certainly those levels are a concern with regard to drinking water...

 


 
Jonathan Kadish said:

In my research on the subject I have read studies that say high nitrate levels can effect the rate of growth in fish.  A level of 40 ppm is pretty high coming out of the tap and has health risks for humans, pets and especially infants. Once your bacteria begin to create more nitrates on top of that you could get into the kind of toxicity that will have an effect on the fish. Do you live in an agricultural area?

I got water tested by a professional water testing company in Honolulu. Looks like the Nitrate testing method used in my testing kit measures something different than that is used by the water board. They used EPA 353.2 method and the numbers they got is 2.58 mg/L. They said the water is safe to drink. So I have to go with that for now. The system is doing very well and we have been enjoying some good harvest. Now I have been moved to Germany for the next 8 months so thinking of starting a new system here.

Thanks again for the help.

Vishnu

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