Awesome. Very crafty Frank. Will that piece of wood fit in here? That wood looks pretty big.

Very Nice Frank..

nice project Frank, keep us posted. Good luck to getting your goal through.

Alex, question for someone with your experience: If I take the Danios out of this 29 gal, and drain it to move it (to build the stand) how long will the water keep useful bio for? I dont want to have to cycle it again, but I need to move it, and build the in-wall stand ....

nice project frank , not sure on life of the bio . could you possibly drain the tank so that you could move it to another spot till the construction is done ? would be my best suggestion . that way theres no worry about bio depletion . save the water though so you dont have to do a complete re fill with fresh.

Water itself carries very little bacteria so keeping the water is almost useless. What will help you is to take whatever filter / biomedia that you plan on using for this tank and put it on a tank that is running while this one is broken down. When you set this one back up fill it 50% with water from an existing tank that way you'll be putting in amonia and nitrite (imediate food for the bacteria you've kept alive from another tank). Harvesting and maintaning several bacteria cultures weather it be a bio wheel, ceramic, sponge, ect is THE MOST important part of fish keeping in my opinion. I also try to have several seperate places on each tank to harvest bacteria. On my 125 I have 9 different places. This way if I get too carried away while cleaning and kill a culture I have plenty to fall back on. Also when I start up or if a friend starts one up we won't have to cycle as I can spare a great deal of mine. Hope this helps.

Sorry Alex, didn't me to "step on your toes" here. Just got a little excited as I have learned this the hard way. :(

"me" = mean

Frank, you may just have to run your filter on you your larger tank for awhile. When your project is done, use tank water from your 72g I believe, Fill your 29g about 30-50% or so with it, then fill with non-chlorinated water. 2 days to a week and you will be running great.

Thanks guys. I cant beleive I didnt think of using my existing tank to keep my filter alive and to fill the new tank once its ready to go... thats what happens when you try to plan your construction/tank setup at 11:30pm on a Monday night :)

Travis idea is great...thats what i do

Hey Frank, a little late to respond, just see you post.
Not much I can add, after Travis.
He suggest the easiest and most convenient way. Actually one extra thing.
I know you live in NY/LI. I know that area very well and I know that you can safely add up to 30% of tap water, right from the faucet, without using any addictives, no stress coat, no chlorine removal, etc. I did 50%, but wont suggest it for others. 30% is safe. It would make easier for you.
As for your original question, water bio condition and how long it will stay useful without any living species.
I agree with Aaron, it’s not useful to keep only the water, very little bacteria there, and will die out quickly since they have nothing to thrive and reproduce. Debris will do for awhile, but what the heck you need that, when Travis suggest such an easy way out, you lucky you have another tank running.
I fed my 210 gal, off my 29 and 55 gal at that time, taking water and rinsing filter media in the new tank.
It's something for you too look, once an awhile rinse existing/running filter media into new tank.
One more thing to mention.
Any running closed circuit filters (canister, etc), at the best condition, will become non-useful and contaminated with dead bacteria, if it's unplug it for longer then 5 hours. Books says even faster, but I don't think so.
All useful bacteria die out without fresh oxygen, filter become more danger then help.
HTH,
Now we all due for several Cutteri, if you breed them:) j/k, ...
Alex

Thanks guys.

No worries Alex - I saw you were on last night, so I tried to post a quick question, but there is no rush.

I'm draining the tank tonight, so that I can build the stand and have the tank setup this weekend. If all goes well, I'm ordering the Cutteri pair to be delivered for next Friday.

Update: Tank is empty. Home Depot run during lunch hour for some wood to build the stand. The stand will hold the tank flush against the wall, about 4 feet high, and will have a shelf underneath for a 10gal fry/sick tank, as well as storage for supplies, food, buckets, etc.