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Discussion Starter #1 (Edited)
I have a 250 gallon reef set up with overflows going into a sump. The sump and tank are completely covered, though not air tight. I've had this tank from my reefing days. The problem is I can't get a pH drop greater than pH= 0.9 and rarely a 1.0 pH drop. I suspect that the overflows could be part of the problem since it introduces a lot of gas exchange into the system (lots of water turbulence in them). I would ultimately like to get at least a 1.2-1.5 drop... I would like to be able to go as far as I need to in order to increase my light energy (measured in PAR) over the tank.

There is inherently so much dissolved O2 produced by reef tanks (overflows/sump) that the CO2 could probably be pushed quite high without damage to the fish furthermore, I am sure that ultimately Decreasing what causes the O2 to rise so high would in turn automatically Increase the CO2 level by preventing less gas exchange.

I have an AquaMedic 1000 CO2 reactor powered by a Sicce 2.0 pump which is what is what is required for this reactor. I push through 100 cc/min CO2 through the reactor. The CO2 obviously never shuts off all day.
The Aqua medic 1000 was the largest reactor I could find.

The tank does ok at this CO2 level when I am running about 80 PAR at the substrate and has been for about 1.5 years. It's when I raised the PAR level to ~120 PAR that I became aware that there just isn't enough CO2 to compensate for the increased metabolic demand of the plants at this energy level! Green algae is now covering most of the plants leaves and sides of the tank. I have to clean the front glass every day. Last night I shut off the extra 2 - T5 tubes and went back to my old light level. I am pretty sure it's from not enough CO2.

I would appreciate any thoughts or solutions regarding how I could increase my CO2 level.
I am scratching my head at this point.
 

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I'm by far not very experienced when it comes to overflows, but is there any way to adjust / add / remove baffles, tubing, sponges etc. etc. to reduce turbulence? Eliminate surface rippling in the main tank and in the sump - rely strictly on the turbulence of the overflow to provide your gas exchange? I guess it would depends entirely on your specific design.

You could keep injecting more and more CO2 until either you reach your goal or you run out of equipment to dissolve it all, in which case buy another reactor and keep driving CO2 into the system... not the best solution I know.

Sealing the sump? Not sure what that would do to your biologicals in there, if you stock light enough you could get away without any biological filtration in the sump...

Run 120 PAR but include Excel / Met14 in daily dosing and see what happens?
 

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Similarly, I had a 220 gallon reef tank with a 65 gallon sump. After 10 years, I decided to take down the reef and convert it to a heavily planted high-tech aquarium.

The tank was designed for reefkeeping. It had a central overflow that fed into a trickle filter in the sump, and had two return pumps, one feeding 4 surface returns and the other feeding an elongated return along the bottom back wall. Gas exchange and water flow was very high, by design.

I was never able to get the CO2 high enough. After many trials, I gave up. I was fighting the design of the tank, and the design won. I turned it into a rocky African cichlid tank and it worked famously.
 

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I'm partial to the Cerges style reactor. I think with 20" housings and a dedicated pump you could run 2 of them inline (join the tops with 3/4 close nipples) with a high water flow rate. You'd have higher flow than would work with just one and you would push a bunch of bubbles through the first one, but they'd then get disolved in the second one. I think you might be able to get quite a bit more co2 in the tank than you're able to get now.

I've wanted to try this for a while but don't have a tank big enough to warrant it.
 

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How many holes are drilled? If you have two, you can do it a herbie style overflow. Thats what I have and I love it. It creates a syphon so no splashes and less off gasing. Super quiet too. I can't tell if it's on.
 

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Discussion Starter #6
Unfortunately, I have the old Durso type overflow with one hole drilled in the back for the overflow, the other hole is for the return pipe. It's a Marineland Deep Dimension tank.

Bump: What type of CO2 system (s) did you try?

Bump:
Similarly, I had a 220 gallon reef tank with a 65 gallon sump. After 10 years, I decided to take down the reef and convert it to a heavily planted high-tech aquarium.

The tank was designed for reefkeeping. It had a central overflow that fed into a trickle filter in the sump, and had two return pumps, one feeding 4 surface returns and the other feeding an elongated return along the bottom back wall. Gas exchange and water flow was very high, by design.

I was never able to get the CO2 high enough. After many trials, I gave up. I was fighting the design of the tank, and the design won. I turned it into a rocky African cichlid tank and it worked famously.

What type of CO2 system (s) did you try?
 

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I had a 20# CO2 cylinder with a Milwaukee regulator, solenoid and needle valve. It fed into a DIY reverse-flow reactor made of PVC that was in-line with one of the pump returns. I was pumping so much CO2 through the system my 20# tank would be empty within a month.

In contrast, a 20# cylinder would last almost 2 years with my heavily-planted 90-gallon sumpless tank.
 

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If you have two holes drilled in the same overflow box you can do the herbie style. You could just pipe the return outside the tank. It would solve your off gasing problem.
 

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I have a 165 with sump. Don’t get to technical. Set your bubble counter at a rate just beyond your ability to count. Inject into the intake of your return pump. Watch your plants. If they are giving off oxygen, your good. Most reef setups use an apex with pH meters and more. I can help with the settings on the apex to control CO2 lights etc if you have one. Basically the pH should drop .5 during CO2 and come back to target at night. My 5lb CO2 lasts around 8 weeks. I use Seachem Flourish and their plant tabs for large Red Rubrum Swords. I harvest tons of leaves every month so plants are very happy. My goal was for planted tank with an overstock of large fish. A 250 is a lot of tank! Have fun
 

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125 gallon display with 55 gallon sump.
I can drop about 1.2 (8 to 6.8) pH in 2hrs with this design. 1.5 (6.8 to 6.5) drop an hour after that. This is with a single 4.5" x 20" cerges reactor.
20# tanks usually last me between 95~110 days.

I'm also pumping about 95~100 cc/min. CO2 is on it's on separate loop.


most recent iteration of what I'm using:

the cap at the end of the loop is just to catch any co2 bubbles that may have got past both reactors.


I think your issue might be because the aqua medic is too small. I'm just going by quick google images.

At your size of the tank you have to consider the volume of your reactor, more volume = more room for the co2 to mix. It's also important to have a valve near the end of the loop incase you need to increase pressure inside the reactor to crush the co2 some more.
 

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It's also important to have a valve near the end of the loop incase you need to increase pressure inside the reactor to crush the co2 some more.

having a valve after the reactor is also really helpful for burping the reactors whenever they get a big gas pocket (especially after initial install or after cleanings). all of the RO housings have a little pressure release button on the top - you just close the valve and push the button until the gas pocket is released, then reopen the valve and you're good to go.
 

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Discussion Starter #13
125 gallon display with 55 gallon sump.
I can drop about 1.2 (8 to 6.8) pH in 2hrs with this design. 1.5 (6.8 to 6.5) drop an hour after that. This is with a single 4.5" x 20" cerges reactor.
20# tanks usually last me between 95~110 days.

I'm also pumping about 95~100 cc/min. CO2 is on it's on separate loop.


most recent iteration of what I'm using:

the cap at the end of the loop is just to catch any co2 bubbles that may have got past both reactors.


I think your issue might be because the aqua medic is too small. I'm just going by quick google images.

At your size of the tank you have to consider the volume of your reactor, more volume = more room for the co2 to mix. It's also important to have a valve near the end of the loop incase you need to increase pressure inside the reactor to crush the co2 some more.
I like your CO2 numbers and your CO2 efficiency! It gives me hope.

Where did you get such a large housing for the Cerges. And are there larger housings out there?
I don't know the first thing about the Cerges design. Do you have any other diagrams or know where I could find out more information about them? Does any company offer pre built Creges reactors?
I would rather minimize the trial and error part of building and installing one of these since there seems to be a lot interest in them.

What do you mean when you say the CO2 is on a separate loop?

I do like the aqua medic design. It's a shame it's not offered in a larger version to increase contact time.

Thank you for your excellent advise!
 

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fwiw i've gotten 20" housings from ifilters.com for ~$60, and they've been great. i haven't seen any pre-built at that size, and i haven't seen any housings larger than that.
 

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I like your CO2 numbers and your CO2 efficiency! It gives me hope.

Where did you get such a large housing for the Cerges. And are there larger housings out there?
got my 4.5" x 20" from [Ebay Link Removed] clear ones are more expensive from what I've seen. Been considering switching over to these: 163828594413 (ebay links are blocked here, I can only post the item number)

I don't know the first thing about the Cerges design. Do you have any other diagrams or know where I could find out more information about them? Does any company offer pre built Creges reactors?
I would rather minimize the trial and error part of building and installing one of these since there seems to be a lot interest in them.
General build guide:
https://barrreport.com/articles/how-to-build-a-cerges-co2-reactor.43/
notes:
in the design referenced in the link above the co2 will mix inside the 1" pipe; personally I recommend having the flow going down the middle pipe instead be cause you would then be mxing the co2 in bigger chamber instead. A valve at the end of the reactor is really important.

Premade:
4.5" x 15"
https://greenleafaquariums.com/products/aquarium-co2-reactor-12-16mm.html

4.5" x 10"
https://www.nilocg.com/shop/na-cerges-carbon-reactor-aquarium/

What do you mean when you say the CO2 is on a separate loop?
The reactor has it's own pump and exits near the main return pump.

I do like the aqua medic design. It's a shame it's not offered in a larger version to increase contact time.

Thank you for your excellent advise!
no problem
 

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Your attempt to bring up the overall co2 concentration in the large tank with sump, I have a different approach.

First of all, it is probably just me with this idea, it is not tested and don't want to lead to any problem if anyone copy it, so correct me if I am wrong.

I have a 160G display with 20G and 50G sump, the actual water volume is about 200G-220G.
Years ago when I started the CO2, I found it was an impossible task to bring the co2 to 30ppm in every part of the tank.
Since then I adapt a method by using the return pipe pushing a high saturated co2 jet stream at certain angle towards the center of the tank where most of the plants are concentrated. The jet stream creates a high co2 saturated current blow over the plants then slows down, dissipated, and mix with rest of the tank water.

I don't aim to increase the ppm(or bring down the PH) to a certain level in the whole tank, only this jet stream carry high ppm of co2.
Most of the plants are constantly enclosed by high co2 current, (the co2 concentration can be much higher than 30ppm when hitting the plants), as long as most other part of the water body is 30ppm or less, fish have no trouble, they get in and out of the current.

it is difficult to measure the exact co2 concentration in certain points of the current, and the value is dynamic, but don't care....

The benefit is:
Even the CO2 is cheap, but don't need to refill a 15lb co2 tank every month or two, ....

simple chart





similar to spherical light intensity chart
 

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I had a 20# CO2 cylinder with a Milwaukee regulator, solenoid and needle valve. It fed into a DIY reverse-flow reactor made of PVC that was in-line with one of the pump returns. I was pumping so much CO2 through the system my 20# tank would be empty within a month.



In contrast, a 20# cylinder would last almost 2 years with my heavily-planted 90-gallon sumpless tank.
Hey Mark... do you have any pics of the DIY reverse flow reactor? It would be great if you had pics of the process of the build too. If not, is it a Cerges type reactor and how is it set up? Thanks!

Sent from my SM-N975U using Tapatalk
 

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125 gallon display with 55 gallon sump.
I can drop about 1.2 (8 to 6.8) pH in 2hrs with this design. 1.5 (6.8 to 6.5) drop an hour after that. This is with a single 4.5" x 20" cerges reactor.
20# tanks usually last me between 95~110 days.

I'm also pumping about 95~100 cc/min. CO2 is on it's on separate loop.


most recent iteration of what I'm using:

the cap at the end of the loop is just to catch any co2 bubbles that may have got past both reactors.


I think your issue might be because the aqua medic is too small. I'm just going by quick google images.

At your size of the tank you have to consider the volume of your reactor, more volume = more room for the co2 to mix. It's also important to have a valve near the end of the loop incase you need to increase pressure inside the reactor to crush the co2 some more.
Hey Tsing... I set up a single 4.5" x 20" cerges using the same flow pattern as your first inline Cerges yesterday. In other words, I have the line from my dedicated pump (filter) feeding the reactor through the PVC inserted into the middle of the reactor. The filter I am using is an FX4 so there's plenty of flow. I bled the system of all air before I started adding any CO2 to the reactor. In a nutshell, this design is not working for me. I do not get dissolved CO2 but, rather, very noticeable bubbles coming into my tank.

I think the reasons you are getting such good results with your design are;
1.) The sheer amount of contact time you have between both reactors and
2.) The build up of pressure in the second reactor by having the water having to be forced up and out of the center PVC piece.

Anyways, I am hoping to have time to take mine apart and reverse the in/out and will report back the results.

Pics of present reactor set up included.



Sent from my SM-N975U using Tapatalk
 

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Your attempt to bring up the overall co2 concentration in the large tank with sump, I have a different approach.

First of all, it is probably just me with this idea, it is not tested and don't want to lead to any problem if anyone copy it, so correct me if I am wrong.

I have a 160G display with 20G and 50G sump, the actual water volume is about 200G-220G.
Years ago when I started the CO2, I found it was an impossible task to bring the co2 to 30ppm in every part of the tank.
Since then I adapt a method by using the return pipe pushing a high saturated co2 jet stream at certain angle towards the center of the tank where most of the plants are concentrated. The jet stream creates a high co2 saturated current blow over the plants then slows down, dissipated, and mix with rest of the tank water.

I don't aim to increase the ppm(or bring down the PH) to a certain level in the whole tank, only this jet stream carry high ppm of co2.
Most of the plants are constantly enclosed by high co2 current, (the co2 concentration can be much higher than 30ppm when hitting the plants), as long as most other part of the water body is 30ppm or less, fish have no trouble, they get in and out of the current.

it is difficult to measure the exact co2 concentration in certain points of the current, and the value is dynamic, but don't care....

The benefit is:
Even the CO2 is cheap, but don't need to refill a 15lb co2 tank every month or two, ....

simple chart





similar to spherical light intensity chart
Hey @Bettatail - the way you have your inflow designed is how I also have mine. However, I am running mine through a 3/4" RFG (random flow generator). I have attached pics of the RFGs that I had my daughter's boyfriend print for me on his 3D printer. One of them is 3/4" and the other is 1". I am wondering if you would get even better CO2 dispersion in your display with using a RFG? Your thoughts?

Oh, and in something unrelated to this thread; I have a question for you regarding flow meters. Would you mind if I PMed you?

Sent from my SM-N975U using Tapatalk
 
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