It is because of the on / off cycle which causes pressure back up and differences in pressure, etc. for a small contained low pressure system like this. It is also evident during the last few days of its life as well but without the Solenoid its pretty stable till the last couple of days or so. You are obviously going to look at more refills and added cost because you will run it 24/7. You could reduce the bps if you are running it 24/7 and check the CO2 levels every now and then in the beginning to make sure you are achieving what you set out for.

Then I'm wondering why Jrill isn't having the same problems with inconsistent bps using the solenoid.

And I'm also wondering; Do you guys think if it is possible to solve this problem with a proper check valve between the solenoid and the CO2 system?

Another question for Jrill: I noticed that you are using this bubblecounter (or a similar one) and was wondering; is that also a check valve? And if not, what kind of check valve are you using?

Yes it does have a check valve but I also have a standard aquarium check valve after that.
My bps is pretty stable until pressure changes a lot. I do need to adjust bps two or three times a week but they are small adjustments. I could probably leave it but am trying to stay as close as I can to the 2 bps while testing formulas.

I wish I had read this thread earlier, becaus I tried to dubble all the amounts as well, but it only lasted 6 days at 4bps. Witch was the same for the original amounts. I think I'm gonna try one of your recipes Jrill.

Ok, thanks for the info. Are you using a plastic or metal check valve besides your 2 in one?
It still doesn't explain why I'm having these inconsistenties, so I'm going to run it without the solenoid for a while, and see how that goes.

Its plastic.

You should note that jrill uses the rolls Royce version of this system with a number of additional custom souped up components . IMHO, you will never achieve stable bps with this system out of the box. Even with a lot of mods and added components you will need to make adjustments like jrill just mentioned.

I guess you're right, but running it without the solenoid does seem to improve the consistency of the bps. Now I'm thinking of getting a new check valve and maybe a better needle valve.


Well somehow this recipe doesn't seem to work for me. Its now day 3 and after turning it on this morning all the CA moved to bottle B. Bottle B still got unsolved BS, so I swirled it around, but that makes the pressure build up quite a lot, of course...
Anyone any idea what went wrong?

You have a leak somewhere.

Mmm, well I checked everything, but couldn't find any leaks.
I replaced the tubing and removed the check valve.
I hope that will fix the problem...

I now try:
CA 300g / 600ml water
BS 200g / 200ml water

Leaks can be hard to find. What method did you use to check.
The reason I think there is a leak is because the system should only move ca to stabilize pressure. During the first three days of a fresh mix I never see any ca move until maybe the end of day three.

... and, STOP.

Using that pro rig, the last recipe and 1.5 bps, I got to 37 days and the tank plants look great.

And that was with only 2 weeks of turning off manually at night. The remaining time the CO2 was left on 24/7. (life intruded)

Hmm. So totals hours of CO2 production was 776, or (based on the 16 hours of lamp time per day) 48.5 days if I installed a cutoff solenoid.

Very cool. I wonder what my production cost using bulk citric acid from my local store would be. I will note the price next purchase.

Thanks for the recipe experimentation folks!

Cool beans. The best prices for me for citric acid has been on Amazon.

I used the method you mentioned; the kids bubbles with foam brush and covered everything with it, but couldn't find any growing bubbles.
But I guess I'll have to try it again because my last batch ran out last night...

Hmm. Something is amiss. Hope you find it.

I think Hoppy said you have to watch it for about 5mins.