Maintaining Co2 Balance in Large Tank without Ph controller

After two years of trying, I still found it impossible to maintain the Co2 level in my 100g tank. Although I tried turning the Co2 on 4 hours prior to lights on, I still wouldn't reach any target consistently several hours after lights on. Only after installing a Ph controller more recently have I been able to maintain the tank without turning it into a BBA zoo.

So I then set the needle valve to maintain my target Ph (6.15) throughout the day running open (so as not to turn off the Ph controller). This worked really well except in the morning I discovered that as before, I couldn't arrive at the desired Co2 saturation level at lights on unless I started many hours prior. For whatever reasons that I can't discern, the tank requires a Co2 boost initially to bring it up to speed. Once there, it can be maintained with a much smaller amount of Co2 being injected quite readily.

If I am to be able to break from the Ph controller dependency, my solution (which I hate because these things always cost more money) is to install two solenoids, and two valves each running on a separate timer. One to be run more open for one hour to achieve the desired level, and another to take over and run open throughout the remainder of the day to maintain it.

I guess my question is this how it's done for large tanks, or am I injecting too much Co2 or? The fish are fine and things are really growing like mad and I couldn't be more pleased. No reason really to mess with it other than to lose the Ph controller. I could always dose less Co2, I just don't want to deal with the algae again now that things are going so well.

I've got good flow running around 10x overall and good mixing etc. Running Eheim 1103 NW w/venturi through Nu-Clear canister. Separate 300g pump pulling through internal trickle filter (sealed)

Thanks

 

Thank you, but I think something else is going on? I can very easily reach the target dose, perhaps in 15 minutes if I tried - but I can't maintain it at that rate without going past my target dose is the problem.

For example I can set the controller to reach a target of X.X. Once there, I can back off the amount of Co2 being injected so as to keep it constant and just above shutting the controller off. Then the next morning, allowing perhaps two hours of Co2 to be injected before lights on, it will still be several hours before the target is reached. The only thing I think of is that my fish, those that survived two years of up and down Co2, are fairly hardy by now and therefore have too much Co2. I've backed it off 1.5 degrees to see how it goes. I wait 3 hours before turning all the lights on and then off an hour before they are all off (thx).

I have the controller because regardless of the method (having used dual reactors/atomizer/diffusers), this long lag time to achieve the target kept me from having any success. For a great while, I'd had a leak in my solenoid but never could find it. Thought I'd have this licked by now, but no!!! I understand the limitations of the controller, and in this case, its usefulness.

I should think someone who has a tank this size might have had similar troubles. I'm betting on too much Co2, at least as long as the algae stay gone. Otherwise a manifold and second solenoid I think would be my last option.

 

Well, if I adjust my needle valve in the slightest Tom, I can see the difference on my controller readout within a few seconds of doing so (I find the Reef Fanatic Ph Controller to be very fast and stable for what it's worth) - assuming the range for testing is within +- 5 degrees. At the extreme ends one must wait perhaps 15 minutes in my experience.

Per the thread Nipat, I am totally lost as to what the solution you describe was?

Thanks all!

 

Well Nipat, as suspected it took over 3 hours (probably 4) to load up even at a somewhat reduced Co2 level. While I suppose I could take it further, then I'd be raising lights and all that.

While I think the process to increase surface flow might be the remedy per the thread (and thanks for the explanation), I have a lot of plants which hit the surface. I found that I was getting brown algae when I increased the surface agitation too far. I do still have reasonable surface agitation along with 300gph going through the trickle filter (which was previously run open with little difference in Co2 loss) so I should think I'm getting the o2 in there.

Hate to have to spend more $$$ on another solenoid and manifold, but I don't see any other way.

Co2 is a lot trickier than I ever imagined.

 

I've got the controller probe in one of the sumps of the built in trickle filter which has 300gph running through it with very little head so the results are quick to show if the Co2 injection rate is modified. In addition, i have an Eheim nw pump running full steam at 700gph. So I think the overall flow should be OK. I can quickly drop the Ph by opening the NV. The results are almost immediate.

The tank otherwise is doing incredibly well, better than it ever has since being able to stabilize the Co2 using the controller so I think this should rule out a flow problem.

 

Dual NV in place

[attachment=1044:name]

So I went ahead and setup my Co2 rig using dual needle valves. One to bring the Co2 up to speed within 2 hours and the other to maintain the Co2 rate at a constant level so as to eliminate the need for a ph controller. Despite the gaggle of fittings, I have to say that this did the trick. One valve runs open at an increased clip while the other at the pre-tested constant rate two hours before. After 1.5+ hours, I turn the first valve off and let the other continue on which brings the Co2 to the desired level by the time the lights come on.

Thought it worth mentioning that initially I ran a second separate nw pump in the tank and found that there wasn't any appreciable difference in the amount of time it took for my tank to get up to speed (as compared to running out a single source with increased Co2 output). As a final check, I tried maxing the surface agitation but discovered that it I only used more Co2 and couldn't get the ph below 6.3 (which isn't low enough for my needs).

Now that the Co2 is perfectly balanced throughout the day with the fluctuations of the controller, I do see improvement in the plant growth and the fish no longer flashing the plants from time to time. Now I just have to remind myself not to change the lighting height or surface agitation without adjusting the NV...

 

I have a tube extending the length of the tank with additional flow pushing towards one end, or close to 10x. Since I now had separate controllers, I tried putting another NW DIY pump on one end. I didn't notice any appreciable difference in the time involved. When i pushed the injection rate much further with either one or both setups, I get larger Co2 bubbles that just head to the surface. While I might be able to get to the desired Ph level within a hour, I think I'd be wasting a lot of Co2 trying as opposed to waiting it out for 2 hours. Weird, I know all too well.

Before the NW's, I used dual DIY reactors and atomizers. The result was always nearly the same. I went so far as to bypass the built in trickle filter before discovering a bad solenoid that was leaking and going back to it. Without the controller, i was always shooting past or coming up short of the mark giving me real problems. Using dual solenoids and NV's seems to work.