My 90 gal. tank has been running without fish, but with plenty of plants for about 2-3 months, after moving it to a new house, and bringing over the filter with its dirty media, and about 30% of the old water. It had fish inside for a couple years before, but they are currently in a smaller tank.
Question is: is the main tank still cycled after so many weeks without fish? A guy at a LFS mentioned to me today that the bacteria will die over time without fish in the tank, even with plants. I guess what he might have meant was that the nitrifying bacteria would die without a source of ammonia. Can a fishless tank with a nasty algae bloom not have any ammonia and "lose" its cycle?
Assuming you still had poop and plants in the tank and the filter media remained wet, you would not have lost your cycle, as there would still be decomposing materials that will be feeding your nitrite and ammonia eating bacterias.
I wouldnt worry about it at all. in the worst case add fish slowly and keep checking for ammonia/nitrIte spikes.
Quote from: "Aiglos"Assuming you still had poop and plants in the tank and the filter media remained wet, you would not have lost your cycle, as there would still be decomposing materials that will be feeding your nitrite and ammonia eating bacterias.
I actually had the water and filter running in a large Rubbermaid tub for about a month (with all of the plants, old substrate, and most of the poop) before I completed the move. Then I set up the main tank with a new flourite substrate (poop-less), the plants, 30% old water and same filter media, and have got that running for about 2 months. Only this last weekend did I clean the filter media after about 3 months. Should I add some ammonia to be 100% sure?
you'll be alright, dont add anything
I would expect, at the very least, a mini-cycle.
The plants would have to functions in this scenario
1) Surface area the beneficial bacteria would be on
2) Decomposing plant material provide SOME kind of nitrogen source.
Now, given that plants preferred source of nitrogen is ammonia (one reason you might not have had any in the tank for a while) and that you had no fish waste creating ammonia for two months (reason two), at the very least the "ammonia eating" bacteria have substantially died off or died altogether.
Just to play it safe, add some ammonia, and then 24 hours later see if you get any ammonia or nitrite readings. Add enough ammonia so you register about 1ppm shortly after adding it (a fishless cycle you usually go around 3... but we aren't really cycling, we are just testing)
Quote from: "BigDaddy"Now, given that plants preferred source of nitrogen is ammonia (one reason you might not have had any in the tank for a while) and that you had no fish waste creating ammonia for two months (reason two), at the very least the "ammonia eating" bacteria have substantially died off or died altogether.
Thanks for the info... Although I have been dosing ferts on a regular basis, the plants are still quite weak and producing a lot of decomposing material, with some of them losing the battle against algae. What is surprising is that I once read that some people have been able to start their cycle with plants only... I guess doing the ammonia "test" will allow me to find out if mine is OK. Where's a good store to get pure ammonia in Gatineau? :)
Quote from: "Poustic". Where's a good store to get pure ammonia in Gatineau? :)
Zellers or Canadian Tire in the cleaning product section and propably the grocery store, once you look, it's everywhere.
The 1 ppm of ammonia that I measured last night was all gone this morning. I put in another 1 ppm and will double-check tonight. I got to say I really like this fish-less cycle thing and can't see myself using fish to jump-start a tank cycle ever again. Plus, there must be enough ammonia in a $2.79 bottle to cycle hundreds of aquariums!
If my calculations are good (6 mL of ammonia for 90 gal gave 1 ppm) it looks like "Old Country" ammonia concentration is about 5%.