Nitrate problems

[John Cubit]

Well I have been running a mini system since last year and it has be running well.  Currently it is as follows:

25 Gallon Tank

10 Gallon Grow bed flood and drain

5 gallon constant flow trough

1 gold fish very large (had 3 at the beginning of last week)

Water temp constant 71.2 degrees.

All numbers on water quality are good

0 - Ammonia

0 - Nitrite

7.4 - pH

80 - Nitrate

Currently we are growing tomatoes (big plants but blossoms all drop), 8 leaf lettuce, 2 broccoli and 8 habanero plants (no blossoms yet)

Starting two weeks ago the fish appeared to be stressed so I removed them and isolated them in a hospital tank.  They were swimming erratically, fins tight against body and laying upright on bottom of tank.  Figured swim bladder so switched to pea diet and after a few days they were all back to normal.  Tank was still test fine.  Did a good scrub on walls to get salts off and increased flow rate to filter out any loose sediment.  Did that for 3 days.

Placed fish back in tank and after 3 days the littlest one just died and the other two went right back to  the same symptoms.  So separated the two fish and quarantined them, back to peas.  Again they recovered.  Replaced the smaller of the two large goldfish and although he remained looking normal he sat at the edge of the tank and watched the larger fish in the other tank.  Refused to eat and then started to huddle on the heater.  At this point I put him back in hospital tank, pulled out the plumbing and put in clean plumbing.  I keep a spare drain set to swap so I can clean the other one without downing the tank.  He still refused to eat and died a day or two later.

I examined this one closely and there was broken blood vessels in the eyes.  Gills slightly red but looked good.  Scales were missing, and there was slight red lines through the dorsal and tail fin.  These are typical signs of Nitrate poisoning, that seems to be verified by the fruiting plants not being able to keep blossoms.

Typically I would not question the Nitrate since 80ppm is not high for AP but with the blossom drops and the blood vessel rupture I am concerned.  I have since place my large GF back in the tank and added additional O2, and increased my drain rates to keep water moving as well as removing the heater, but the fish is swimming on the bottom on its side.  It is still eating but will only eat peas.  He goes up right and starts swimming normal but it looks forced

Question is has anyone else experienced Nitrate poisoning and if so what can be done other than evacuating the whole system and replacing all the water in the tanks?

I know some are going to say Nitrite or Ammonia but I have been a long time with Aquaculture and this is not damage from either.

[John Cubit]

So while on this discussion, and Bill as for dirt operations I fertilize with a 2-2-2 but most of my plants are peppers, tomatoes are just for testing as they grow quickly, and ap is in testing phase for me at this point till my greenhouse is finished being built.

Has anyone used hydrosufite salts to lock out Nitrates?   Does anyone know of anyone know of the effects of it on fruiting plants or greens?  Lockout agents are a waste for fish tanks but what about in growbeds, it can kill the bacteria and a large dose I suspect would wipe out a growbed of all bacteria.  I have at this point removed my FT from the growbed and have now determined that the growbed it what is hurting the fish.  The abundance of bacteria and Nitrates in the grow bed are what is effecting the tank.

I removed the tank and replaced with a fishless 10 gallon tank to feed the 10 gal GB and 15 Gal Trough.  New water and after 24 hours reconnected.  Water was 6.8ph and 0 across the board, with re-circulation through the grow bed after 24 hours the water retested as follows.

ph - 7.3

ammonia - 0

Nitrite - 0

Nitrate - 60ppm (Down from 80)

Repeated the water change again Nitrates are now 40ppm.  This was not what would be considered a partial change but a full water change x2.  Leaving only about 1 gal of water in the gb while things were changed.  This would be considered practical for hydroponics but this is not a practical solution when fish are involved here.  Lucky enough I have but one Comet left but a practice like this would cause heavy stress on him.

I gather my overall solution would be that in fact I could have taken the 25 gal FT and really feed 30+ gallons of growbeds to keep bacteria in check, any thoughts on that?  That would me the theory of 1:1 (FT:GB) is really false and the fish species needs to be looked at more than the FT:GB size.