Yeah I just set this 20t under my tank and realized how tight it will be. Definitely going to have to run a 20 long or a storage container like bob suggested. Do you have to be careful on the type of plastic you make it from? and what is the best way to protect from a syphon break and overfilling my display? Do you think it would be worth it to just invest in say a trigger systems sump/fuge? I would like to build my own but if I'm just going to end up fighting it later on and risk ruining either my tank or carpet i will probably just invest.
All that is the reason to setup a test system in the garage. Actually, even the more expensive refug/sumps have the same exact problems and IMHO require the same exact testing. And fail in the same exact way.
What I do on hob overflows is put an air line to the tube/pvc on the hob part and connect that tube to the "bubbler" on maxijet powerheads. I found I had to use the largest and it sucked out 2 u tubes in about 20-30 seconds. Besides you have to have some circulation anyway. May as well suck out any air in the hob syphon.
Also see test 3 above. I test by failing the siphon and adjusting sump water level so the pump runs dry before the display floods. I then return to normal operation and mark the water level on the sump. From that point on I never never add water (top off, water changes) above that line. That will insure the display never floods in a drain failure and that adjustment is necessary even in a drilled tank with no siphon. Afterall, drains can and do block.
again while you're playing around and thinking about it, pretend your 20g is your display tank and setup a test system in your garage. Afterall, storage containers and pvc are very expensive much less expensive the cleaning up after a flood in the family room.
Even with pvc, storage containers etc, you should be able to prime the water trap (or outside box) turn on the power, and the system will establish siphon and start normal operation with no flooding.
