Why would you buy water with chlorine in it? That will just screw up the cycling of the pond and kill the necessary bacteria.

We have a well, and seeing we ran out last summer, cannot risk that again. The chlorine in the water is very slight. I know people with ponds that have gotten the water, and they said within 2 days, with pumps running, all traces were gone. With power washing the liner - I don't think there will be any good bacteria left, that is why I am adding bacteria after a couple of days, before I add the fish back in. Don't know what else to do about the water - 5000 gallons is alot.

Ah I see. Yes if it is just chlorine and not chloramine then you can off gas that in a few days, or use sodium thiosulphate to neutralize it, which is what I would do. It sounded like you were intentionally getting chlorinated water instead of non-chlorinated.

I don't understand why you want to toss the lava rock. That's a bunch of cycled filter material full of good bacteria. Getting rid of that completely and starting fresh will just set your cycle back. Do you not have sufficient mechanical filtration before the trickle tower so that it is really clogged and nasty?

Are the diy mat filters in 55 gallon drums?

I turned the trickle tower off last year when winter was coming - and have not turned it back on yet - so all the bacteria has died off. This is normal, living in Central NY, it is turned off every winter - just have a pump bubbling on the surface, and hopefully keeps a hole in our average of 4 - 5 feet of snow. Yes, the diy mat filters are in 55 gal drums, and when they get cleaned - are cleaned with well water - no chlorine. I guess I can somehow figure out how to pressure wash the lava rock - this whole process is going to take me to the edge, lol. I know when it is done, it will probably turn green before it cycles thru, but hoping not too bad. Thanks for your help

I see, I would have thought the tower would have been running for a while already.

No, didn't want it running with the so much grud in the pond.