How bad is an HOB filter?

I've got a 20 long with a kh of 11. I've got pressurized CO2 on it hooked up to a Red Sea 500 reactor with the reactor putting out as much CO2 as possible. However, I cannot get my ph down to 7.4. It continues to hover at 7.6. The HOB filter is a Rena, which I haven't been very impressed with and I have the flow rate turned down as low as possible.

Any suggestions? Should I just get rid of the HOB filter, or are other HOB filters friendlier to injected CO2? I have an older Model Whisper 3 HOB that I could use that I could also turn down the flow rate on.

I'm trying to get my ph to a level that neocardinia shrimp will like. I have the ph on my 29 set at 7.2 to 7.4 and my shrimp breed like crazy and my plants grow like crazy, and the regulator isn't constantly in the ON position with CO2 flowing to the tank.

Alright, I already know that surface agitation is a problem, I'm just wondering if a planted tank can be done with a HOB. Has anybody done it.

Affording a canister filter isn't a problem either. I own 4 Fluval 405 and a Fluval 205. I have a Fluval 405 in the closet not being used right now. The problem is that the 20 gallon is not on a stand that lends itself to the use of a canister filter very easily, unless I want to cut holes in the top of the counter. More like drill holes in it. Now that I think about it, that might not be a bad idea. I could also buy another 405 and put it on my 10 gallon tank just for the heck of it and drill another set of holes in the counter top.

Another option for me would be to buy the Fluval filters that go inside the tank, but I would prefer not to if I can make the HOB filters I have work. I think the Fluval filter is called the Fluval U4 or the Fluval 4 Plus, both of which are underwater filters.

Anyway, back to the original question. Has anybody had any success with a HOB filter on a planted tank with CO2 injection? If so, what are you recommendations?

67chevelle said:

How do you set your PH?

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I have a ph monitor/controller on almost all my tanks. In this tank and in my 29 gallon tank I set it at 7.2 and when it hits 7.4 it turns on the CO2 flow via the regulator. CO2 causes the ph to drop, so it goes back down to 7.2 and the controller closes the regulator. In essence, I never have to worry about the ph in my tanks and they always stay 0.2 from where I set them, unless the filter bleeds off the CO2 quicker than the reactor can replace it and/or the plants use the CO2 faster than the reactor can replace it. On my 120 gallon setup, I was running 3 Red Sea 500 reactors and they were struggling to keep up. So, I went with a Red Sea 1000 reactor attached to a pump and a dispersing bar that I manufactured, and I kept one of the Red Sea 500 reactors in the tank and it seems to be working great now. The regulator only comes on for about 5 minutes now before the ph is back to where it should be.

I also never have to worry about the CO2 to the plants so long as I keep the ph and kh at the correct level and the reactors can dissolve the CO2 quick enough.

Hope that helps.