Inefficient Ext Reactor.

[cherabin]

In my war against BBA, i have upped my CO2 BPS by quite a considerable magnitude. However, i have realised that tiny bubbles are coming out from my filter outlet and at the same time, the reactor is filled with water till about 80% with the rest of the volume being CO2. Is there anyway i can better 'dissolve' the CO2?

I am using NA ext reactor with an Eheim 2226. Not using rainbar on filter out and the outlet hose measures about 1.3m from reactor to the tank. Many thanks and really appreciate all advice.

[PeterGwee]

That's O2 degassing...not CO2. You can consider returning the outlet of the reactor with a spraybar at the bottom back of the tank as long as you have some surface movement.

Regards
Peter Gwee

[BFG]

Peter, how does this degassing occur?

[PeterGwee]

Peter, how does this degassing occur?

BFG, the O2 level goes above 100% due H2O splitting from photosynthesis process by plants.

Here is a better explanation...

I've been secretly doing some test using a DO meter, chamber tubes and an IR to see about gas build up and efficieny of CO2 reactors. Perhaps not radical, but few have really looked at this issue in this much detail.

O2 levels are directly correlated and proprotional to gas bubble build in CO2 reactors, wereas the CO2 levels are not.

In testing this idea, I needed to maintain the CO2 level. This was a problem since at higher levels with plants, the O2 levels exceeded saturation and outgassed in the chambers.

We have all seen this gas build up occur diurnally as the photoperoid progresses throughout the day. Many folks have asked why this occurs. Well, rather than sitting around wondering...........

This off gassing of O2 greatly reduces the efficiency of a CO2 reactor when you need it most, near the last half of the day.

After about 4-6 hours of intense lighting, the O2 levels are sky high.
I measured the gas build up (In millimeters) in the reactor tube and graphed it next to the O2 levels(ppm).
Next, I did the same for CO2. CO2 went down while the O2 continued to match the reactor tube level.

I tried my internal designs and they did super though. the O2 levels rose, but so did the CO2 levels.

Why?

The venturi loop I added to my old design some 10 years ago.
This is the same venturi loop I have on the DIY internal Reactor here:

www.BarrReport.com

At first glance, the venturi appears to waste CO2, but it's really there to pruge O2.
This pruging allows the reactor to operate at a higher efficiency dissolving CO2.
Some folks asked why I added that. Now you have the reason, I needed to prove it first though.

Internal reactors have little issues with gas lock and flow reductions.
I have recently designed a DIY External reactor that pruges the O2 in a similar manner.
This removes the gas lock and O2 build up automatically and gets back to the business of dissolving CO2 when you need it, during the day.

An interesting note: the Sintered diffuser stones do not have this O2 build up, nor does the internal DIY reactors I've posted plans for. So that is one good thing about the snintered stone diffusers, all the gas is CO2 coming out of them. There are trade offs with them also(Clogging and maintenance, good flow is needed to to diffuse through the larger tank sizes and other issues). FYI, if folks are interested, I know a company that also sells 1"x6" stones much like the airstones but at 100-500micron bubble sizing for around 55$. I am not affliated with the company nor do I sell these. This size of stone would be enough for a 200 gal tank or so. Unlike the ADA products, these can be placed on the substrate or under wood etc hidden from view rather than on a side or back glass pane.

I'll post a DIY externals venturi loop design in a few days. These will give the best response of any reactor designs for our needs and also be cheaper than any commercial products internal or external.

Enjoy,
Regards,
Tom Barr

Cherabin can consider doing the venturi hole if he uses a powerhead to drive the reactor instead of the filter but make sure it is sealed well.

Regards
Peter Gwee

[cherabin]

BFG, the O2 level goes above 100% due H2O splitting from photosynthesis process by plants.

Here is a better explanation...


Cherabin can consider doing the venturi hole if he uses a powerhead to drive the reactor instead of the filter but make sure it is sealed well.

Regards
Peter Gwee

I was about to ask the question about degassing but seems like BFG beat me to it

Many thanks Peter for the detailed explaination. Next query is how to i diy a venturi loop? Definitely wouldn't mind adding a powehead if it reduces the O2 degassed.

[BFG]

I get it now. All this while, I thought my canister filter ( 2222 ) has not enough 'punch' to push out the water from the canister filter to the external reactor. I was a bit perplexed, thinking that co2 had accumulated in the reactor but when I turned the reactor upside down to release what I had thought to be co2, there were no co2 poisoning occuring to the inhabitant of the 2ft shrimp tank. Now I know more. Thanks Peter for the link.

[PeterGwee]

I was about to ask the question about degassing but seems like BFG beat me to it

Many thanks Peter for the detailed explaination. Next query is how to i diy a venturi loop? Definitely wouldn't mind adding a powehead if it reduces the O2 degassed.

Cherabin, you can view the DIY internal reactor design w/venturi that Tom came up with which I posted in the beginner section and go about doing it for the external reactor (the external reactor that you had might be a bit difficult to work with...don't crack the whole thing). Its just a hole 2-3 inches down from the top of the reactor. Connect a rigid tubing to the hole and route the line back to the powerhead driving the reactor. Do not make a burping hole though.

Regards
Peter Gwee

[Green Baron]

Cherabin, you can view the DIY internal reactor design w/venturi that Tom came up with which I posted in the beginner section and go about doing it for the external reactor (the external reactor that you had might be a bit difficult to work with...don't crack the whole thing). Its just a hole 2-3 inches down from the top of the reactor. Connect a rigid tubing to the hole and route the line back to the powerhead driving the reactor. Do not make a burping hole though.

Regards
Peter Gwee

Peter,
Do you think we can also add a venturi tube to the green internal reactor by adding a loop back hose ?

[Plantbrain]

Some other brand?
Sure, not a problem.

Regards,
Tom Barr

[PeterGwee]

Peter,
Do you think we can also add a venturi tube to the green internal reactor by adding a loop back hose ?

Yes. You can also remove the bio-balls and bottom cap to facilitate more flow. Just model it after the design posted in the beginner section.

Regards
Peter Gwee

[Green Baron]

Yes. You can also remove the bio-balls and bottom cap to facilitate more flow. Just model it after the design posted in the beginner section.

Regards
Peter Gwee

I have those with 3 balls. I remove 2 balls and that fixed the problem with stucked balls. I don't think I will remove the bottom cap as that might stir up the dirts at the bottom of the tank and reduce water circulation. I will try adding the venturi loop instead.

[cherabin]

My CO2 reactor is really driving me crazy The degassing has caused the external reactor chamber to be filled with O2 by about 50% despite the fact that i have changed my filter output to a spraybar located at the bottom side of the tank.

I reckoned my CO2 BPS should be around the region of 10 in a bid to stop the further propagation of BBA. Is there any other better alternatives to better dissolve the CO2?

[|squee|]

10 per second?? What's your size tank? 10 per second is crazy imho. Perhaps there's something wrong with your kH and pH test kits?

[cherabin]

10 per second?? What's your size tank? 10 per second is crazy imho. Perhaps there's something wrong with your kH and pH test kits?

Tank size is 4 x 1.5 x 1.5. I'm disguested by BBA and hence would rather pump up the CO2 concentration way above the 30ppm mark. When i use to inject 5-6bps, the KH and pH test already gave me a good result but somehow or rather, BBA still plague the tank.

Would the Dennerle Cyclo internal do a better job than the NA ext?

On a side note, it's only the Lilaeopsis brasiliensis and Cryptocoryne nurii that are badly hit by BBA, for the other plants, the infected area is more or less negligeble. Any reasons for this? I'm tempted to remove all the brasiliensis and use tenullus for foreground instead as it's much faster growing.

[|squee|]

I don't know, but I'd ensure good circulation too. The present BBA in the tank should be removed. CO2 stops the growth of BBA, but won't kill the BBA already present in the tank.

[cherabin]

I don't know, but I'd ensure good circulation too. The present BBA in the tank should be removed. CO2 stops the growth of BBA, but won't kill the BBA already present in the tank.

Thanks for the prompt reply My filter IO is located on the same side of the tank with the reactor running inline, does that provide good circulation? Or should i locate the IO at opposite ends of the tank. There seems to be 2 schools of thought regarding this.

I am already applying H2O2 treatment slowly, in order not to stress out the fauna. How long would it take the BBA to go away upon application?

[PeterGwee]

Is the BBA actively growing or just sitting there? Remove all traces of it and see if it grows back. If the CO2 is indeed high and good, the BBA will not grow.

10bps seems way too much for a 4ft tank. 2-4bps seems a better rate for a tank of that size.

Regards
Peter Gwee

[cherabin]

Is the BBA actively growing or just sitting there? Remove all traces of it and see if it grows back. If the CO2 is indeed high and good, the BBA will not grow.

10bps seems way too much for a 4ft tank. 2-4bps seems a better rate for a tank of that size.

Regards
Peter Gwee

Growth of the BBA seems to have come to a standstill. I am trying my best to remove all traces of it but the brasiliensis is badly infected. 2-4 bps sounds good to me but i was pumping this amount of CO2 initially and the BBA came, hence i am reluctant to go back to this rate.

[vinz]

Ok, I'm jumping into this thread late...

I'm using NA custom built external CO2 reactor on a 6'x2'x2' tank. Even when my tank had a large volume of plants which were producing O2 abundantly throughout the day, I've never had more then 10% of the reactor filled with gas.

Let me state upfront, I'm not disputing Tom and Peter about the degassing of O2 into the reactor chamber. But I don't think 80% to 50% of your reactor filled with gas is due (completely) to O2 degassing. Your bps is too high.

I don't think I've ever gone above 3 bps for this tank. So, I don't think you need 10bps. 2 to 4 bps as suggested by Peter should be good enough.

Come to think of it, how did you get 10bps? IME, bps that high becomes a continuous stream that is impossible to count. Are you sure you counted correctly? How do you count your bps?

During the time my tank was in the above condition, it was running on a filter with a output of 1000 l/hr, so your 2226 with 950l/hr should be efficient enough for this reactor.

I think your problem is more with circulation. Do you notice the BBA growing only in certain parts of the tank and not others?

I've had BBA problems with this tank before, but due to poor circulation. re-directing or re-positioning the spraybars solved my BBA problems.

How are you positioning your spray bars?

Check your filtration loop for flow obstruction.
1. Are your hoses clean?
2. When was the last time you cleaned the filter media? Especially the fine wool?
3. Don't over-pack the fine wool... it will slow down the flowrate. Make sure the topmost tray is not filled to the brim and has space for the fine wool... it will compact the fine wool and make it harder for water to flow thru.
4. When was the last time you clean the filter impeller and housing. Including the inlet and outlet valves?
5. Check the hoses for kinks.
6. Make sure the hoses are not overly long. (Try to make sure the hoses do not dip too low.)
7. Check the positioning of the hose in the middle of the external reactor. If you have removed it for cleaning before, the hose might not be position properly. If that hose drops too low into the hole, it blocks water flow. You may need to modify it. See the attached picture. It shows the base of the reactor. In the modification, I cut the end of the hose diagonally and make sure the open side faces the water inlet.

Consider splitting your filter inlet into two and positioning the inlets at different ends of the tank.

[vinz]

Having good CO2 does not necessary mean that the existing BBA will die and go away by itself. Best to physically remove as much as possible. Cut and remove the infected leaves. If the entire plant is infected, remove the most infected ones and leave some leaves for the plant to photosynthesise. When new leave/shoots grow sufficiently, remove the remaining infected leaves.