How high for tanks on bottom rack?

[Stealth Aquatics]

Hello, I’m planning on having a mini stand built to hold some 20S below my work table. How high should the tanks be off the floor so I can gravel vac and change water okay? 

[KBOzzie59]

If you use a power vac they can be on the floor.  If you are using a siphon vac they need to be high enough to get a reasonable siphon going.  My lowest are a little over 1 five gallon bucket off the floor.  The bonus with this height is I can store the buckets under the tanks.  You will also want to make sure you have plenty of room above the tanks for netting fish out and maintenance.

[Andy's Fish Den]

The racks that I have built for tanks with 10 or 20 gallon on, the bottom of the tank sits 16" off the ground. I also leave 8" of space between the top rim of a tank and the bottom of the shelf above to give room for netting fish out and getting in to do water changes etc. 

[Stash Beardsley]

I have some 4" off the floor and use a siphon hooked up to a sink. The lower tanks siphon slower but doesnt bother me.

[anewbie]

I had a 20 long that was 4" off the floor and it was a royal pia. I had to use an active pump to do water changes which in itself was a pia. Also it was a pia to work above the tank since the tank above it was about 12 inches - it was such a pia i upgraded it to a 40 and put the 40 at 30 inches high - though being lazy i waited 9 months before the upgrade.

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Of course the reason to do it is space savings esp if you are going to try to fit 3 tanks in a column - so that is the trade off - I would recommend at least 8 inches off the  floor and at least 18 inches between tanks but if you have an active pump you can go as low as you want and the gap between the tanks - well that is dictated by trade off of easy of working with the tank vs number of tanks per column. 

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Oh one other thing to consider is bending over - of course if the top tank is too high you will need a ladder so there is that to consider. 

[Elser]

I have a 20 long that sits about 13inches from the floor. This seems to be just enough to get a symphony going but I had to shorten the tubing on my gravel vacc to basically come up/out of the tank and straight down into the bucket 5 gallon bucket. 

[Stealth Aquatics]

I think I’m going to leave the 20s bare bottom and use a power head to pump for water changes, and it will be about 8 inches off the ground which is high enough for a 2.5 gallon bucket to be lower than the tank, that way I can spot vacuum. I think that should work.