Those of us with Wet/Dry filters

I run one.

For me, and this tank in particular, I think the key is low GPH and placement of the CO2 dispersion unit or powerhead as far away from the overflow as possible.

My KH is higher than yours, but I monitor that weekly and adjust it upwards with baking soda, to around 3.5. I have a smart monitor that kicks the CO2 in around the 6.6-6.7 range. That gives me around 20-25 mgL of CO2, which is a comfortable range for me.

And the plants seem to love it.

With a wet/dry sump style you do have to "Pump" more co2 in. I have a 20lb bottle of co2 and it lasts about 2 to 2 1/2 months thats it (and only running the co2 when the lights are on about 11 hours a day) and I get a stable ph of 7

Good luck

I have recently (May) set up a 120 gal (4x2x2) with wet-dry. I am struggling to keep my pH at 7.0, and to do this I have to stream my CO2 into the intake of my submersible pump at a huge rate!

I have ordered a plantguild CO2 power reactor, and I know that will make some difference over not using any reactor in my system.

But I discovered an interesting thing by accident: I did my usual water change, but over filled my tank such that the bioballs in the sump were almost completely covered. In other words, I am using a 20 gal tank for my sump, and the water level in the sump was about 3 inches from the top. I left it this way. The interesting thing is that later that day (maybe 8 hours later), the pH was down to 6.5!!! Nothing else was different in my setup. Therefore I deduced that the water cascading through the bioballs is causing a tremendous out-gassing of CO2.

The main thing I like about the wet-dry is the surface skimming, otherwise, I would have started with canisters to begin with. I may switch to canisters yet, but will wait and put the CO2 reactor on, see how the pH goes, before making a big investment and switch filters.

I may try changing my sump media around. Instead of a rectangular holding pen with bioballs, and the water dripping through a drip tray through them, I am brainstorming about using a cylindrical column holding pen, maybe 8-10 inches in diameter. Then I would have the water first flow through "filter fluff" (standard polyester stuff) as the first filter media in the cylinder as a prefilter. this would be above water line. Then the water would flow down through some permanently submerged filter material, similar to what happens in a canister filter.

Originally posted by Jamie
Timmain, How big is your tank and what is your GPH? I was considering slowing down the flow but was wondering what is safe/unsafe. Your experience would be helpful.

also, I purchased the aquarium pharmacueticals Master Test Kit as my major "laboratory". What do you, or anyone else reading, use and are you satisfied with the quality of the product. I'm a bit skeptical about mine. Considering the importance of KH and pH in determining CO2 Concentration, I would prefer to have a reliable means to test for them - allthough I do have a Milwaukie(sp) pH control that displays the pH.

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The tank is the one listed in my signature. It's 240g/200g in-system/400-800WPG@peak. I'm running a "QuietOne3000" cranked back to about half, so about 400GPH or 2x water change an hour. I have a manifold return in the tank so water is pumped back into the tank at the left-top end and also at about the middle bottom, for better circulation.

Strangely enough, I got tired of the "Master Test Kit" and bought a Hagen KH/GH test kit. It works quite well. The smart CO2 system that I bought can be found here. The only part of this system that I am dissatisfied with is the CO2 reactor.

And I agree with the others, CO2 tends to burn off quicker with a W/D. I have two 10lb bottles that I switch out, and it takes about 4 months to go through each 10lb bottle on the 240.

Originally posted by The Gipper
I may try changing my sump media around. Instead of a rectangular holding pen with bioballs, and the water dripping through a drip tray through them, I am brainstorming about using a cylindrical column holding pen, maybe 8-10 inches in diameter. Then I would have the water first flow through "filter fluff" (standard polyester stuff) as the first filter media in the cylinder as a prefilter. this would be above water line. Then the water would flow down through some permanently submerged filter material, similar to what happens in a canister filter.

Click to expand...

I was going to suggest a sponge of some type for replacement of the bioballs. I've seen others do this so that they don't have to go Berlin with their W/D plant tanks. I am considering removing my bioballs as well, as they don't seem to be serving much purpose.

And that's an OPINION now, not gospel. I'm experimenting just as much as anyone else here.

The power outage issue is a valid concern. I don't normally fill my tank so much that the sump is within 3 inches of top. Usually the sump (20 gal) is about half-full.

the thing about the bioballs being in air as I understand things is this: For biological filtration you provide a media upon which the beneficial bacteria can grow. The greater surface area the more space to accomodate the beneficial bacteria. Bioballs have incredible surface area. The benefit of having them above water is that these beneficial bacteria do their thing best with maximum oxygen, hence suspending them above water level. Some people even air pump air into the bioball chamber to increase O2 levels. They bacteria still needs to be wet, hence the constant dripping of water. If the bioballs are submerged, and you flow water over them you are still supporting the bacteria, but maybe not as much O2 as having them in air. So I would guess the biological filtration is not as efficient as if theywere in air, but it's still there. And as long as you don't get ridiculous about fish stocking it should be fine.