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Discussion Starter · #1 ·
Hi all,

I recently set up pressurised co2 for my 140L (37 gallon) tank, mostly to assist my hair grass carpet attempt. It's a co2 art pro-se with a diy reactor. Reactor seems to be working ok how ever does get some co2 collecting at the top. I have also tested with in tank diffuser with same results. I have triple checked for leaks.

Co2 comes on 2 hours before lights and Tank is normally 25 degrees but can spike to 27 on hot days. I have large rocks in the tank and black iron sand and black diamond sand as the substrate. I have 850 L an hour canister filter.

Every where I read suggest that 1-2 bps should be plenty for that size tank, however I've had to raise the bubbles count to 4 bps to have an effect on the drop checker and now running at 5.5 bps. High bps doesn't bother me Im just worried about how quickly I'll be going through my 2.6kg tank.

I know bps is not accurate due to different size bubbles etc but it just seems significantly more than what is usually reported for my size tank.

Any tips or ideas what could be causing the issue? Could it be that due to the rocks and my substrate that the KH of my tank is quite high causing co2 diffusion issues?

P.s I have a pH pen and attempted to get a 1 pH drop but at 5.5 bps I can only manage a 2.6 drop.

Please let me know if you would like more info.

Thanks

Greg
 

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That is actually right in line for a tank your size.

My high tech 25 gallon tank was running 4.75 bubbles per second.

Your drop in pH is probably fine, it's best to tank a sample of tank water before the CO2 comes on, leave it out for another 12-24 hours and thern test pH. I bet you are hovering around that 1.0 drop when the tank water is fully degassed. Tank water does not fully degas overnight / the next day until the CO2 comes back on.

Most people running CO2 are no where near the limit, hence the bubble per second reports you are reading. That's why on tanks any bigger than yours, bubble counters are not needed, instead, a flow meter is preferred so we can accurately measure the flow of gas in a volume rather than trying to count bubbles. If you want to spend the money, a Dwyer RMA-151-SSV is what a lot of us use.

For example, my 45 gallon tank holding 44 gallons of actual water is running 25 cc's of CO2 per minute. This would be a constant stream of bubbles in a bubble counter = impossible to count. My 5Kg CO2 tank lasts me 6 months at this rate.

The best advise would be to treat CO2 as if it's free, in the grand scheme of things, CO2 is inexpensive and running it a constant rate ~1.0 drop in pH is worth the price.

I hope this helps. Sounds like you're off to a great start with this tank.
 

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Discussion Starter · #3 ·
That is actually right in line for a tank your size.

My high tech 25 gallon tank was running 4.75 bubbles per second.

Your drop in pH is probably fine, it's best to tank a sample of tank water before the CO2 comes on, leave it out for another 12-24 hours and thern test pH. I bet you are hovering around that 1.0 drop when the tank water is fully degassed. Tank water does not fully degas overnight / the next day until the CO2 comes back on.

Most people running CO2 are no where near the limit, hence the bubble per second reports you are reading. That's why on tanks any bigger than yours, bubble counters are not needed, instead, a flow meter is preferred so we can accurately measure the flow of gas in a volume rather than trying to count bubbles. If you want to spend the money, a Dwyer RMA-151-SSV is what a lot of us use.

For example, my 45 gallon tank holding 44 gallons of actual water is running 25 cc's of CO2 per minute. This would be a constant stream of bubbles in a bubble counter = impossible to count. My 5Kg CO2 tank lasts me 6 months at this rate.

The best advise would be to treat CO2 as if it's free, in the grand scheme of things, CO2 is inexpensive and running it a constant rate ~1.0 drop in pH is worth the price.

I hope this helps. Sounds like you're off to a great start with this tank.
Hi Quagulator,

Thanks so much for the reply, you've really put my mind at ease regarding my co2 set up.

Took your advice and kept a cup of tank wanted out, it's now been 14 hours and it is showing 8.03 (assuming high pH due to high KH due to rocks and my substrate) and my measurements today of the tank droppee to 6.8 within two hours of co2 and stayed at that pH for the remainder of the co2 period. So I'm getting a drop of approximately 1.23.

Going to dial back my co2 a touch to try to reduce drop to 1 point as my clown loach seems to be behaving differently. All other fish are 100 percent fine/normal behaviour.

Will post some picture tomorrow.

Cheers

Greg
 

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Hi Quagulator,

Thanks so much for the reply, you've really put my mind at ease regarding my co2 set up.

Took your advice and kept a cup of tank wanted out, it's now been 14 hours and it is showing 8.03 (assuming high pH due to high KH due to rocks and my substrate) and my measurements today of the tank droppee to 6.8 within two hours of co2 and stayed at that pH for the remainder of the co2 period. So I'm getting a drop of approximately 1.23.

Going to dial back my co2 a touch to try to reduce drop to 1 point as my clown loach seems to be behaving differently. All other fish are 100 percent fine/normal behaviour.

Will post some picture tomorrow.

Cheers

Greg
Hi Greg,

I would not dial back CO2. The 1.23 drop is perfectly fine. The 1.0 we recommend is a starting point only. Some of us with higher pH's drop it 1.6 or so even.

If the livestock seem fine, you are good to go.

If you are more concerned, aim the filter outlets at the surface, install a surface skimmer or run a small airstone at night to help gas exchange.

Aim for high O2 + high CO2 in the water and everyone will be happy.
 

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Discussion Starter · #5 ·
Thanks Quagulator,

Took on your advice once again and aimed the outlet towards the water surface and kept co2 the same. After two hours pH dropped 1 point rather than 1.2 as per the previous day's and the drop checker was slightly darker at end of co2 period. Clown loach seemed much happier so that definitely seems to be working. Hopefully it also helps with the oil slick layer on the surface too.

Looked into the surface skimmers, might try find one I can attach to my canister filter. The glass ones looked good, although I'd have to modify my aquarium hood first to fit.

Cheers

Greg
 

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IMO, @Quagulator is offering particularly good advice on all aspects of CO2 measurement and balance with O2. I run CO2 24/7 and pH and O2 are rock-steady 24/7. The high gas exchange (I use a surface skimmer - they’re cheap) is the reason. With high gas exchange, you will have to increase CO2 supply, slightly, to achieve the desired level, but it is inconsequential in the cost of CO2.

My pH drop is in the 1.5 area. Your loach will adjust to higher than a 1-point drop if you wish more CO2, especially if you max-out on the O2, which can be measured, on a relative basis, with inexpensive kits like the Salifert O2 kit.
 
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Discussion Starter · #7 ·
Thanks Deanna, Definitely will look at getting a skimmer.

Here's a pic of my tank. Was never meant to be a planted tank so wrong substrate and substrate it only about 1cm thick at the front and 4 cm thick at the back but seems to be working.
Hopefully with the co2 the hair grass fills the gaps promptly.

Cheers greg
Plant Plant community Rectangle Green Nature
 
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