Co2 Injection Ph Swings

[bjanbkboi]

I once had a diy yeast CO2 injection system in my 10 gallon tank. When I checked the pH it was about 6.5 and it's usually 7 w/o CO2. I don't want to alter the pH too much for the health of my fish but I do think my plants would benefit from extra CO2. I have a water conditioner that says it buffers the water to a pH of 7.5. Would this prevent big changes in pH or should I just forget about the CO2 all together? Btw My lighting system is one power-glo 15 W fluorescent bulb.

 

[Liam]

The ph swing wont harm your fish at all. A drop of one point in a couple of hours doesnt cause any stress to the fish. PH is often used as shorthand for the amount of dissolved solids in the water, its a change in the TDS (total disolved solids) that causes problems for fish as they need to keep a balance between the salts in their bodies and the salts in the water. A half point drop from 7 to 6.5 is fine, the only potential problem is when the water doesnt have a high enough buffering capacity anything lower than a KH of 3 or 4 can cause a ph crash. If a ph of 6.5 is okay for the fish you have then there is no reason to stop using the Co2.

 

[Themuleous]

That's not strictly true Liam

Indeed a pH swing of 1 point shouldn't affect the fish at all, people have been doing large water changes of CO2 tanks for years with no problems. However, pH is not a measure of TDS, GH is a very simplistic test for TDS, pH in fact is a test of the relative concentrations of free hydrogen irons in the water, 100% hydrogen is pH 1, 0.00000000000001 is pH 14.

Also yes the buffering capacity of the water is important but ADA aquasoil activity reduces the pH of water by removing KH (buffering capacity) as such anyone who uses aquasoil will likely have a KH that is undetectable by aquarium test kits, and they don't experience massive pH swings. For the less experience a KH of down to 1 should be more than adequate. But in such circumstance its best to large weekly water changes to ensure the KH doesn't drop further.

bjanbkboi - don't whatever you do, use the pH buffer solution, I'm hugely sceptical as to how effective they are and in your situation its completely unnecessary. Also those potions more often than not contain phosphate buffers which will affect the plants in your tank (read the bottle ). You'll also be fighting a loosing battle, as you'll have to add it every time you do a water change. Just leave the tank as it is, the plants and fish will be fine

Hope that helps

Sam

 

[2pods]

So what happens if my KH is below 3-4 ?

I have a fine gravel substrate and usually keep a filter bag full of crushed coral in the tank.
This gives me a pH of 6.8 with the lights on. (I tried to check just before the tank lights went on, but forgot about light coming through the window ).

My Co2 kit is (hopefully) on it's way, but I don't want to kill my fish.

Peter

 

[Dave Spencer]

My tapwater is 4dKH and it drops to somewhere below readable with CO2 injection. I have a steady pH, or at least I did the last time I tested it, which was a long time ago.

The bottom line is, for the pH ranges operated in various tanks, the best pH is a stable one with nothing added and nothing taken away to alter it.

Dave.

 

[2pods]

My tapwater is 4dKH and it drops to somewhere below readable with CO2 injection. I have a steady pH, or at least I did the last time I tested it, which was a long time ago.

The bottom line is, for the pH ranges operated in various tanks, the best pH is a stable one with nothing added and nothing taken away to alter it.

Dave.

Hi Dave

Before I used the coral the pH was very prone to dropping, and KH was unmeasurable.
I just don't want to lose any fish.

Would be alright to PM/ping you via the board when my Co2 kit comes ?

Peter

 

[Themuleous]

How come your pH/KH was so low? Your tap water cant be that soft! do you have any wood in the tank?

I can't think of a single person having said they have actually experienced a pH crash, have you? Nothing should happen if your KH is below 3-4, only at undetectable levels do you need to 'worry' but even then this is not a problem so long as you keep up the regular water changes.

DAVE - if you read this, how come your KH dropped below detectable when you added the CO2, CO2 (or the resultant carbonic acid) shouldn't affect the KH that much and if it doesn't it'd take months to reduce 4dKH to below 1dKH?

Sam

 

[2pods]

How come your pH/KH was so low? Your tap water cant be that soft! do you have any wood in the tank?

I can't think of a single person having said they have actually experienced a pH crash, have you? Nothing should happen if your KH is below 3-4, only at undetectable levels do you need to 'worry' but even then this is not a problem so long as you keep up the regular water changes.
Sam

It's the notorious scottish soft water

I change 25% weekly.

Peter

 

[Themuleous]

Haha dam you and your soft water, what I would give not to have to use an RO filter! . Even soft water must have some KH, would still think it'd be fine. If needs be (and mostly for environmental reasons) a better way to increase the KH would be to add bicarbonate of soda at each water change rather than using crushed coral, you have to ask yourself where the coral comes from. Its like using peat on gardens. But that's just the eco-warrior inside me talking.

Sam

 

[2pods]

Haha dam you and your soft water, what I would give not to have to use an RO filter! . Even soft water must have some KH, would still think it'd be fine. If needs be (and mostly for environmental reasons) a better way to increase the KH would be to add bicarbonate of soda at each water change rather than using crushed coral, you have to ask yourself where the coral comes from. Its like using peat on gardens. But that's just the eco-warrior inside me talking.

Sam

Yeah, everyone has stolen our peat, so I'm going to use their coral

The coral was a pressie from someone who had given up marines.
Originally I was going to use oyster shell.

Peter

 

[Dave Spencer]

DAVE - if you read this, how come your KH dropped below detectable when you added the CO2, CO2 (or the resultant carbonic acid) shouldn't affect the KH that much and if it doesn't it'd take months to reduce 4dKH to below 1dKH?

Sam

I must admit that I don`t know. I use the JBL KH test kit which seems very accurate when I use it on my CO2 dropper 4dKH reference solution, but it always turns yellow on the first drop in my aquarium water. I haven`t done the test in a while so I`ll give it another go. It`s just that my tank is on the other side of the room and it is such a long walk.

Dave.

 

[Themuleous]

You lazy sod!
Does seem strange though.