[bioguy]

I've got a new 35 gallon tank planted with Vals, Sagittaria, and 2 types of Swords. The plants died back during tank cycling and it took about a month for this to stop and get to 0 Ammonia and 0 Nitrite. It was capable of cycling a teaspoon of Ammonia over night. I understand tanks well but this is my first true planted tank.

I added the first fish, 12 small (1cm) Green Tetras and the tank got VERY cloudy within 18 (mostly at night) hours. Ammonia and Nitrite have risen but are within the low range. I understand NTS but this seems like a very low bioload considering the amount of rotting plant the tank was converting prior to adding fish.

This has never happened to me.

The only new variable is that the tank had thriving colonies of several types of micro-life---daphnia, cyclops, limpets, 1/2 cm flatworms, small nematode looking worms, something tiny that the cyclops were hunting and something that looks like a fan coral (suspected hydra)---that developed while the tank was cycling (I got my plants from an established Shrimp tank that had these at low densities). When I put the Tetras in they went crazy and appeared to feed no stop for a couple hours (on something to small to see...the same thing the cyclops were eating if I had to guess). While I can't imagine the nutrient load from this feeding was sufficient to cause a crash, could the Tetras have consumed so many of the "unidentified critter" that the food wed went out of whack...allowed bacteria to bloom leading to the cloud.

 

[bioguy]

I think you misunderstood. I cycled the tank with time and a tad off ammonia. I planned to use fish but as the plants died back (I presume to transplant shock NOT cycling) I thought it would provide the nitrogen needed to fuel the cycling. After the nitrite and ammonia went down to 0 I considered that it might be because the plants were no longer dying/decaying so I added ammonia to test my filter bacteria...ie. see if it would go all the way to nitrate or get stuck in the nitrite phase (I don't think the plants could metabolize that much ammonia). Since Ammonia and Nitrite went to 0 overnight I felt my filter bacteria were doing well enough. My understanding is white cloudy water is due to bacteria (not nitrogen cycle bacteria but others) and green cloudy due to algae. I figured the "other" bacteria may have been kept in check by whatever the Tetras ate. I guess the simple question is has anyone seen a NTS like white cloud bloom, caused by disruption of micro fauna in a tank. I've never had NTS (which is what this seems like) even after adding an equivalent bioload, but I've also never had a tank with a full foodweb in it before I introduced my fish.

I clarified this in the original post.

 

[bioguy]

Tank is back to normal after 48 hours and a 5 gallon water change each day (with RO water). Weather the bacteria bloom was due to bioload or micro food web disruption is academic at this point but if anyone has a thought it would be appreciated.