padra":2q8j0lkd said:
"Rubbermaid sump is often used"
yeah, i figured so. like with hydroponics
my concern was with the plastic.. not food grade and would you know if they chew it. urchins like spending time hanging on the glass
also, does a large external filter act as the sump? i'm a bit confused with the filters as you might have noticed. when i first read about salt-water tanks everything pointed to under gravel filtration, then i read about bio-wheel filters and thought they were the new and improved method, now ive seen these external units that look quite complex. in my application i need gear that is as mainenance free as possible, even at the cost of easy change filters/carbon/whatever
Well, the reason they spend time on the glass is to forage for algae, but I don't think they would chew into the sides too much. Your need for a chiller makes some plumbing necessary. An inline chiller unit needs feedlines. A drop in unit-not sure about avilability where you are at- might work but it can't be in the main tank it must be in the sump.
An external filter is just that-a filter. A sump is a secondary tank situated under the main tank and plumbed to drop water by gravity to the secondary tank where it is filtered, skimmed, etc. The water is then returned to the main tank via a pump. They are used to house extra equipment instead of in the main tank and for additional water. More water in a system equals more stability which equals less maintenance and means you can keep more animals in the same space.
Also, a simple top-off device could be placed there, as you have read I am sure that water evaporates out of the system daily (raising the specific gravity) and needs to be replaced with treated freshwater.
A standard sump with a wet/dry filter should do everything you require with very little in the way of maintenance. It could also be constructed by using a rubbermaid tub.
Also, if you wish to avoid extra plumbing, you could (possibly) use a drop-in chiller unit in the sump rather than one that is plumbed inline. But, chillers are NOT my forte so I hope to have others post up here.
padra":2q8j0lkd said:
hoping not to drill holes either. its why im thinking a tub rather than glass.
i'd like it to never ever leak and because lab stuff is prone to rough treatment i could see silicone seals eventually giving out.
are the pumps not powerful enough to hang a hose over the side?
Drilling holes and installing bulkheads in rubbermaid tubs are very easy to do and have a good track record. It's when you drill glass that things get tricky! The way a sump works, i.e. a gravity feed by having an internal overflow (one hole drilled) which sends water to the sump where it is processed, and then returned via a pump to the main that can be made out of PVC rather than another hole. The problem with using a pump to drop the water down is balancing it with the pump pushing it back upwards! It doesn't work very well. Also, the more pumps in a tank, the more heat is generated. There are external overflows, but they tend to be less reliable. I'm attaching a picture of a sump I had under my 125 gallon so you get an idea.
Also, there are a ton of very smart guys in the DIY (do it yourself) forum who have made their own tanks, and could contribute a lot to this discussion. You might consider starting another thread there, and referencing this one here (you can copy the URL of this thread and paste it in the new one.