Cycle crash

[C.w.deegan]

I wanted to redo my 20 gal tank, I removed all the fish and snails and drained the tank completely removed the sand substrate (wanted to do a glass bottom) then replaced the decorations rocks and driftwood I am still using the same well established filter and media my question is would the 100 percent water change and removing the sand have crash my cycle. I haven't added the fish back in yet they are in a different tank for they time being.i can always re cycle the tank I just want to know if it's necessary or not

 

[Aiken Drum]

No way of knowing.

You will lose some beneficial bacteria as some will be living on your substrate and decorations. If you are careful with your filter and dont let it dry out you should be able to retain most of that. Whether the amount you lose causes a noticable crash with your cycle, no way of knowing. Its likely you will see some spike in ammonia and/ or nitrite. If your filter is oversized and there is enough media to support an increased amount of bacteria then the spike is likely to be short lived and your cycle will catch up quite quickly. If your filter and amount of filter media is already at capacity and you are relying on beneficial bacteria finding its way back into the tank onto whatever new aquascaping you will be doing, then it will take longer for your cycle to catch up. Squeezing out an established sponge into the water could get some bacteria onto your new aquascape a little quicker.

 

[C.w.deegan]

OK thank you I'm going to put the fish back in when I get home from work I'll keep a eye on my parameters I didn't let my filter dry out I kept all the media in a bucket of tank water so most of the filter bacteria should have survived I'll take some media out of one my other tanks and add that as well to help out it's not a very high bio load at the moment but i plan on adding more fish to the tank I'll give the cycle some time to re establish and test my water regularly for the next few weeks