The Planted Tank Forum banner

Cant get CO2 levels high enough in tank with overflows w/ sump

7K views 30 replies 12 participants last post by  Edward 
#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.
 
See less See more
#2 ·
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?
 
#3 ·
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.
 
#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:


What type of CO2 system (s) did you try?
 
#4 ·
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.
 
#7 ·
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.
 
#17 ·
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
 
#9 ·
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
 
#10 ·
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.
 
#12 ·
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.
 
#16 · (Edited)
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
 
#19 ·
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
 
#21 ·
If you decide that the reactor approach is not feasible, you may want to try a diffuser approach. I tried this: https://www.plantedtank.net/forums/9-equipment/1276035-co2-tube-diffuser-new-design.html#post11087045 for about a year and it worked beautifully. I went back to a reactor only because of a change in plumbing space allowed me to do it and a smaller tank (29 gal) allows easier use of a reactor.

Since the tube diffuser is cheap, it might be worth a try. You could lay just one long line, or multiple lines, to test it first. Perhaps a combination of the tube diffuser and the reactor may get you there.
 
#25 ·
On the subject of co2 distribution I think the laminar/gyre type flows were my favorite although they were hardscape dependent



the gyre pump pushes a nice sheet of water across the surface and then rolls down the opposite side and circles back up. Having the return pipe at the opposite end allows the gyre to distribute the co2 around the tank.

word of warning for anyone with a 125 that's 72" x 18" x 24;" a Jebao SCP-150 maybe too damn strong for the tank even at the lowest setting, at least that's what my experience was.

BRS has some nice videos on gyre flow


 
#27 · (Edited)
The problem is I can't get a pH drop greater than pH= 0.9 and rarely a 1.0 pH drop. … 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.
If it helps, I also run the AquaMedic 1000 CO2 reactor but on 125 gallon. It has a dedicated pump and a sponge pre filter. I found it necessary to have the reactor filled with the supplied bio balls otherwise the gas escapes before it can dissolve. Here are some of my results,

pump Eheim 1250 (300 gph, 28 W), 1 airstone 24/7, CO2 15 ccm 24/7, 2 inch gas on top, drop checker 5 dKH green-yellow #adff2f colour

pump Eheim 1250 (300 gph, 28 W), 1 airstone 24/7, wave pump Koralia 425 gph, CO2 20 ccm 24/7, 2 inch gas on top, drop checker 5 dKH green-yellow #adff2f colour

pump Eheim 1250 (300 gph, 28 W), 1 airstone 24/7, wave pump Koralia 425 gph, CO2 50 ccm, 6 inch gas on top

pump Eheim 1060 (555 gph, 60 W), 1 airstone 24/7, CO2 15 ccm 24/7, 1 inch gas on top, drop checker 5 dKH green-yellow #adff2f colour, 1.7 pH drop


You have a pump Sicce Syncra 2.0, 550 gph, 32 W which should do the job just fine. I don’t see any other reason why you cannot get more CO2 to dissolve than the reef setup.
 
#28 ·
drop checker 5 dKH green-yellow #adff2f colour



pump Eheim 1060 (555 gph, 60 W), 1 airstone 24/7, CO2 15 ccm 24/7, 1 inch gas on top, drop checker 5 dKH green-yellow #adff2f colour, 1.7 pH drop
Not related, but I was wondering why the 5dKH vs the 4dKH you see floating around the internet? I don't think it matters much but I'm curious,

Thanks..
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top