CO2 rates

[noddin0ff]

I keep reading, but I can't quite get my mind around it all. I'm still getting a 100 gal tank ready for apistos. I've installed a pressurized CO2 system that's using a Red Sea CO2 Reactor 500. I bubble the max the reactor can dissolve with out bubbling over (about 3/sec). My pH dropped from 8.0 to 7.5. Still not acidic.

I was expecting (on no factual basis) a bigger drop. I do use a big trickle filter/sump so I'm sure I lose some CO2 there. I could cut back on the flow rate , I'm sure it's over 200g/h but it's easier to leave it as is. The inflow is distributed over a large spray bar.

My water parameters according to Mardel's 5 in 1 test strip. Are 120ppm for hardness and 40ppm for alkalinity. It is well water. pH is from a probe. My NO3 is never above 20ppm. I do 30-40% changes weekly.

I'm just trying to figure out if this is about right. I'm going to make a DIY reactor with a gravel filter (~2" x 12" and a 100 g/hour pump). Can anyone generalize how much CO2 I can expect to dissolve? I never see a rate of dissolution given on these DIY reactors.

Annecdotally, how much CO2 can you get in? Is it bad to push it to the max as long as the pH is regulated?

 

[kingborris]

sounds to me like your trickle filter is doing an extremely efficient job of stripping CO2 out of the water, and that your CO2 reactor just cant keep up. From the pH / KH / CO2 tables, I'd say you only have around 3ppm of CO2 at best. with an alkalinity of 40ppm (2-3dKH) you'd ideally want the CO2 to lower your pH to around 6.5-6.6. For this you will need a decent inline reactor achieving high rates of CO2 absorbtion. i'd go for something like this:

http://www.plantedtank.net/forums/diy/33344-100-co2-dissolution-inline-power-reactor.html

you will burn through a lot of gas to work against the trickle filter, but this is one of the effects of trickles... massive gaseous exchange.

position the reactor on the return line of the sump, so all water entering the main tank has been through it. Then measure the pH in the main body of water itself. this should give the best results IMO.

HTH

 

[noddin0ff]

sounds to me like your trickle filter is doing an extremely efficient job of stripping CO2 out of the water, and that your CO2 reactor just cant keep up.

That's what I was suspecting. As it is I have a 10lb tank so I suppose I have a lot of gas to burn. The pH probe and reactor are basically side by side next to the intake of the return pump. I've got a big sump so the waters pretty calm over by the submerged pump and there's really little to no air exchange on the return. I'm kind of committed to the sump now since I had to dissemble the stand to get it in.

Maybe I can tame the splashing where the water dumps into the sump. It essentially splashes down on 5" of bioballs above the H2O level in the sump. LOTS of air. On the plus side, very effecient biological filtration. I could probably make a makeshift chamber in the sump to accept the overflow so the overflow emerges below water level and moves up to the bioballs.

I basically want to make something like this
http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=9918&N=2004+113779
to put in the sump. Think it would keep up?

 

[apistoireland]

I'm not sure what this thing should do or why they advertise that it is suitable for a seawater aquarium. Adding CO2 to a seawater? For what purpose?
What you should do is get your hardness down and your pH will follow. Might I suggest that you use some RO water and add it to your tapwater. You could use rainwater but since you live in London I couldn't tell you if that is such a good idea since it might be polluted. If you can get it checked out in a lab do so since this will probably be cheaper in the long run then using RO water especially if you pay water rates.
I would also get rid of the trickle filter if you are intending on growing plants. It will get rid of most CO2 no matter how heavily you dose. You will also save on electricity since your heat loss through the filter will be minimised

 

[noddin0ff]

I'm not sure what this thing should do or why they advertise that it is suitable for a seawater aquarium. Adding CO2 to a seawater? For what purpose?
What you should do is get your hardness down and your pH will follow. Might I suggest that you use some RO water and add it to your tapwater. You could use rainwater but since you live in London I couldn't tell you if that is such a good idea since it might be polluted. If you can get it checked out in a lab do so since this will probably be cheaper in the long run then using RO water especially if you pay water rates.
I would also get rid of the trickle filter if you are intending on growing plants. It will get rid of most CO2 no matter how heavily you dose. You will also save on electricity since your heat loss through the filter will be minimised

It's just a tube you can flow water through counter to the flow of CO2. I don't know why they say marine either. I'd just run CO2 through an airstone at the bottom and H2O from a small pump throught the top.

I'm not really wanting to get into RO. The nice thing about well water is you can just add it as is. I just hook up to the sink, adjust the temp, and fill. It seemed to me that the alkalinity was at the low end of the scale.

It sounds like my next move is to moderate the CO2 loss from the overflow to the sump and at least double my CO2 dissolution...and see what happens.

I haven't tried Peat yet either. Everything I read says it can help but I don't see how.

 

[Oldsan]

You don't need a fancy inline reactor, they work fine but there is little evidence that they're any better than bubble diffusers or even just running the CO2 into a canister filter intake. If you want to make the biggest difference on CO2 levels, you have to minimize water turbulence at the surface, in your sump and in your tank. Otherwise, all you are doing is adding CO2 to the air in the room. This is the reason that a trickle filter is not normally suitable for a planted tank. You won't miss it though - if you have plenty of healthy growing plants (enough light + CO2 + nutrients), your water will be cleaner and more oxygenated than any filter is capable of.

As for marine application, CO2 is commonly used in reef tanks to disolve the media in a calcium reactor.