Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

Quick question for the community: Are there forms of nitrates or things that a water test would register as nitrates that cannot by cleaned up by plants? The reason I ask is this: As soon as I completed my system (cycling and all), I had started to grow out some plants to get ready for fish. I wanted to use tilapia, because I knew that they were good for beginners. Illinois, however, requires you to have an aquaculture permit and a system inspection to raise any fish that is not on the approved species list of Illinois. Finding this out a little on the late side, I had my system all ready for fish and was forced to wait seven or eight weeks for the permit process to work out. During that time, I put in some maxicrop to give my plants something to work off of until I could get some fingerlings. (I added a qt. to a 300 gallon fish tank, with an equal volume of growbeds and a large sump tank) That addition of liquid seaweed product skyrocketed my nitrates off the charts (160+)  Because it's grown warmer outside and we've gotten some rain, I've been able to do water changes more consistently and bring that number down. But I'm noticing something strange with my water. I've started feeding the fish again, had a brief ammonia spike, and then things went back to normal. Every water change brings my nitrate levels down (they are at about >80ppm right now), but the levels don't go down unless I do a water change, they simply remain constant. Nothing added, nothing taken away. I feel like there is a load of waste in my system that the plants are ignoring, but they are taking care of the rate of nitrates that are coming in.

Views: 207

Reply to This

Replies to This Discussion

Hi Alex,

Every water change simply means we are removing very valuable minerals which the system and plants require. The Nitrates are meant to be controlled mostly by type of feed/feeding rate/fish stock/ type and plant density etc.

Yes, I understand that water changes aren't ideal. But I have something in my system that refuses to be absorbed by my plants. How else would you explain it? There's no sign of a dead spot; there's no sediment in the tank. I have a total of nine tilapia fingerlings that are only a couple inches long. And I've had them on a extremely light feeding schedule all winter (once a week or week and a half) and I also make sure to siphon out any feed that they miss. Plus, they've been cold and stagnant this winter, so they've hardly been producing any waste. And my grow beds are chalked full of plants. As soon as I started feeding my fish more frequently, I had an ammonia spike, so I know that I haven't been having a constantly large influx of ammonia. I'm basically just trying to get my nitrates to an appropriate level and then let it function properly. It's kind of like starting over; I had a foundational problem with my system that needed correcting.


Harold Sukhbir said:

Hi Alex,

Every water change simply means we are removing very valuable minerals which the system and plants require. The Nitrates are meant to be controlled mostly by type of feed/feeding rate/fish stock/ type and plant density etc.

Hi Alex,

Yea, I've had problems with building Nitrates myself, and i understand what you're going through. You have constraints which I never had, especially with fluctuating temps. Nevertheless, I changed the type of feed/ feeding rates and what i found of greatest impact was when i put fruiting plants in the system. Since then, if i really need to lower Nitrates in an AP sys. I put in a vine crop(eg. bitter melon) and prune the crop as it grows to get the numbers under better control.

BTW, cute sys you have there!

Since putting some cucumbers in my system the nitrates have plummeted. They seem to guzzle NO3 like it's goin' out of style...

Wow, a whole quart of MaxiCrop eh? Hehe...

I'm relatively certain that only NO3 would show up as NO3...but I'd have to look into that one.

...and check the NO3 level of your top up water...

Yeah, one quart. That seem like too much? I was just going off of what Sylvia recommended.

http://theaquaponicsource.com/faqs-cycling/  (all the way on the bottom under "When Do I Add Plants")

Thanks Vlad, I'll check my water. But my nitrates just remain constant unless I do a water change and since I have an oversized sump tank, I don't top off that often. But my plants are looking healthy :) And my fish are totally happy despite the high nitrates.

Vlad Jovanovic said:

Since putting some cucumbers in my system the nitrates have plummeted. They seem to guzzle NO3 like it's goin' out of style...

Wow, a whole quart of MaxiCrop eh? Hehe...

I'm relatively certain that only NO3 would show up as NO3...but I'd have to look into that one.

...and check the NO3 level of your top up water...

Reply to Discussion

RSS

© 2020   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service