DIY sump filter design, partII

Ok, I have revised my plans for my sump filter I will soon be building. I was originally going to use my current 75G tank as a sump, but after realizing for my purposes I dont need to build walls and such inside the sump I figure I'll just use a really large tote or tub of some sort. Will be cheaper and I really wont be able to use my 75G cause I'll need to have the sump up and running before I can break down my old tank (dont know what I was thinking there :duh: lol!).

Here is a pic I snapped of my sketch (scanner isnt working). Click for larger pic.


First, the overflows will have 2" pvc down to the bottom of the sump, were I can wrap a media bag around the ends to catch larger debris. I was thinking somewhere along the lines of 12"x18" 250micron media bags. This would be a prefilter of sorts, and probably be cleaning out weekly. Should be easy to clean. Then the main filter will be in another smaller tote placed inside the tub. it'll have two return pumps, perhaps with a spraybar looking intake tube to equal out the suction across the whole filter. Spaced above this will be eggcrate with lots of potscrubbers for bio filtration (a gallon or two of potscrubbers?). Another eggcrate and some filter floss ontop for the filters main mechanical filtration. I am not sure the micron rating but I have a large roll of big als filter floss 24"x120" that I can cut out large squares to use. Then the lid will be placed ontop to retain everything in the smaller tote - with large holes cut into the lid. Rena micro bubblers will also be routed into the filter and into the intake tubes of the return pumps to bubble co2 into the return line (this will be a heavily planted and co2 injected tank).

So, before I put hand to wrench is there any flaws anyone sees or perhaps improvment suggestions? I didnt show heaters but they will be placed in the sump as well, along with any other equipment or probes I might include like additional pump to drain the tank for auto water changing, etc.

The drains will be inside the main tub, near the bottom, the arrows aren’t necessarily water flow, they point to where the unit will be placed since its kind of an exploded view and the picture shows everything out of the tub. Think of it like a pond, the main tub is the pond, with a pump in the middle with a prefilter box its sucking though, and it pumps it out of the pond to a waterfall or in my case the main aquarium. I dont foresee the inner part floating (there isnt going to be any air trapped anywhere I would hope) but if it did it should be hard to weigh it down, the pumps might actually go inside the inner box so I wont have to make up some kind of bulkhead fitting to pass then through. Its important that the drain lines are submerged under the water level and that I do not use a drip style system since I'll be injecting co2 and want to retain as much as possible. Yeah the main tub I hope to get something 50G or larger, while the smaller filter box will probably be much smaller. I haven’t figured out the amount yet, but figuring roughly 10-15% daily water change (24-36 gallons drained from sump) I would still want the filter to be working during wc so the remaining water in the sump will still need to be higher than the lid on the inner box so water continues to circulate. I'll have to figure out what combination of tub and tote will get me those sizes. I could also tip the inner box on its side, with the pump still on the bottom, so it would continue to work down to a few inches of depth, just that it would then only be going through a small portion of the filter pad. Another slight change I am thinking would be to build a box around each pump rather than putting both in one, that way I could remove one for maintenance while the other is unaffected.

Some have said you can do wet/dry with co2, it has a lot to do with sealing it up somewhat so that higher levels of outgassed co2 build up around the bio balls and as such less will outgas once the ambient levels are higher. But you still end up using substantially more co2, and probably reduce the effectiveness of the wet/dry to the point where it makes no sense. I pretty much already decided that in the 'part 1' prior to this thread. To be honest, there is little need for bio filtration in my setup, a few have run heavily planted tanks with sumps with nothing more than mechanical filtration, since the plants themselves absorb ammonia, nitrates, etc, they also provide more surface area for beneficial bacteria than what I would be putting in a filter. Think of the sump as mainly for access to the water for dosing and testing and putting equipment, also providing good mechanical filtration (I hope) and lastly to have bio media incase it is needed, almost more as a backup. For a fish-only tank the trickle wet/dry would be perfect but not needed on my design. To be honest I dont think either would be any easier than the other, and at least my fully submerged design would minimize most of the chance of noise (also going to be using a durso style standpipe of course).
As far as co2 injection I did hint to that on the design as well. For a sump you dont need the fancy reactors, a simple micro bubbler feeding into the return pumps is usually all that is necessary - the impeller in the pump shops up the bubbles into very fine bubbles, much like I am doing now with a powerhead in my tank, but these bubbles will either entirely or mostly diffuse into the water by the time they travel through about 6 foot tubing or more to get back into the tank. Although I would like to mist some co2 into the tank it will probably all dissolve I am assuming.