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CO2 drop checker or PH drop, which to go with?

Nick potts

Nick potts

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Joined
25 Sep 2014
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Torbay
As per the title really.

I have 2 drop checkers in a 60cm tank, one at each end, at lights on these are both green, though darker green than I would like. I also have a PH probe in the tank, this reads 7.2-7.3 before CO2 comes on and drops to 6.1 pretty quickly once on. I don't know how accurate the PH probe is but it is consistent every day with little variation. The bubble rate (I know it doesn't really help) is around 7-8bps directly into the filter intake.

Which would you go by?

CO2 is still a big learning curve for me.
 
Both IME/IMO
get a stable pH and wait to see what colour the DC changes the colour change can take some time IME. Then use the colour change as an approximate indication of the [CO2] at the pH which the probes is showing.
If your happy with the [CO2] then you have the pH to aim for for lights on, Time how long it takes to reach the pH and you have your pre lights CO2 on time.
Getting a stable pH is tricky, I personally call stable no increase or decrease greater than 0.1pH from lights on till CO2 off
 
Thanks @Zeus.

I am pretty happy with the CO2 and it does stay stable during the photoperiod. I will time exactly how long it takes to drop and how much it varies tomorrow, though I would be surprised if my PH probe is accurate enough to give me a 0.1 range. The only thing that threw me was the DC being a darker green and how much I am injecting in such a small tank (40ltrs)
 
foxfish said:
You are right that the bubble count is only a guide and only relevant to the individual tank, however I would agree that 8 bps is a lot for 40lt so there might be other issues like flow.
Click to expand...
I thought it seemed a lot, my eyesight isn't the best, so maybe I'll get a slow mo video.

Flow is one area that should be good. Tank has a 1000LPH filter as well as a powerhead in there.
 
Nick potts said:
I am not sure TBH, I am not even sure there is an issue with the CO2
Click to expand...
Hi @Nick potts

There is an issue with the CO2 if you're needing to inject 7 - 8 bps into a small tank. You say that it's 60cm but I can't see the shape of the tank. Please provide the other two dimensions.

Thanks for the photos. I can see that you have livestock in this tank. They wouldn't be very happy if CO2 was much in excess of 30ppm.

Are you able to measure the KH of your tank water? If so, what is the KH? I'm wondering if your KH is very low, say, less than 1.5dKH. May I also ask why you are injecting CO2 directly into the filter intake. And, do you have any additional info about your pH meter? Manufacturer? Model No? Last time calibrated?

JPC
 
Thanks JPC

To answer some of your questions.

The tank is 60x30x22 shallow

KH is 1 or under according to the test I have just done, the test went straight to yellow, I am using RO water, I will say I don't test often.

Filter intake is used after trying a few other ways, powerhead and just having the diffuser opposite the flow, this way seems to be most efficient.

PH is just a cheap monitor, think I paid less than £50 for it, I doubt it is very accurate, but as long as the readings are consistent I am happy with that.

The surface has a ripple to it, also runs through a surface skimmer

Plants have a good sway but nothing damaging, fish seem happy enough with the flow.
 
Nick potts said:
I do, but I do keep my TDS low.

What difference would a low KH make?
Click to expand...
Hi @Nick potts

KH, or as it's more accurately known - Alkalinity - provides buffering to help maintain a stable pH. Without it, there is nothing to prevent pH dropping to a very low level. If your KH is very low (and, particularly, GH), your fish may lose electrolytes. But, admittedly, they look fine. If I'm identifying them correctly, it looks like you have Cardinal Tetras and an Otocinclus. You would need to check on Seriously Fish to confirm the minimum recommended hardness (GH) for these species.

Please confirm your current TDS reading.

And, at this point, I must call it a day. Back tomorrow, hopefully.

JPC
 
Hi @Nick potts , A very low KH tends to make the pH fluctuate more - but fish/plants likely don't care in a healthy tank, as it's all about what makes up the acidifying/alkalizing components. Raising the KH to say 1-2 will stabilize it. There is, as far as I know - and I would like to get more educated on this - (I've read that nutrients uptake in plants are somewhat improved at higher KH? ) no real benefit of keeping the KH super low except that it shaves off TDS which lowers osmotic pressure, if you're worried about that, say if you breed soft water fish, keep delicate shrimps etc. I keep both my tanks at 1-2 KH and my GH at 6-7 (which is fine for Cardinals and Oto's - which I keep in both my tanks) for the same reason as it gives me more headroom for a lot of fertilizer and still keep my TDS down at around 250 ppm. which is perfect for Neocaridina davidi (Red Cherry Shrimps) as well.

Oh, did I mention your tank looks great! 👍

Cheers,
Michael
 
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jaypeecee said:
Hi @Nick potts

KH, or as it's more accurately known - Alkalinity - provides buffering to help maintain a stable pH. Without it, there is nothing to prevent pH dropping to a very low level. If your KH is very low (and, particularly, GH), your fish may lose electrolytes. But, admittedly, they look fine. If I'm identifying them correctly, it looks like you have Cardinal Tetras and an Otocinclus. You would need to check on Seriously Fish to confirm the minimum recommended hardness (GH) for these species.

Please confirm your current TDS reading.

And, at this point, I must call it a day. Back tomorrow, hopefully.

JPC
Click to expand...

Ah yes, I am aware of KH buffering etc, I thought I may be missing something with CO2/KH 🙂

They are neons in this tank, my GH is around 4-5 and TDS is around 140 (will test in a bit)

MichaelJ said:
Hi @Nick potts , A very low KH tends to make the pH fluctuate more - but fish/plants likely don't care in a healthy tank, as it's all about what makes up the acidifying/alkalizing components. Raising the KH to say 1-2 will stabilize it. There is, as far as I know - and I would like to get more educated on this - (I've read that nutrients uptake in plants are somewhat improved at higher KH? ) no real benefit of keeping the KH super low except that it shaves off TDS which lowers osmotic pressure, if you're worried about that, say if you breed soft water fish, keep delicate shrimps etc. I keep both my tanks at 1-2 KH and my GH at 6-7 (which is fine for Cardinals and Oto's - which I keep in both my tanks) for the same reason as it gives me more headroom for a lot of fertilizer and still keep my TDS down at around 250 ppm. which is perfect for Neocaridina davidi (Red Cherry Shrimps) as well.

Oh, did I mention your tank looks great! 👍

Cheers,
Michael
Click to expand...

Yes I am not worried about the PH fluctuating, it seems pretty stable though

I would usually aim to keep my KH higher (well assume it higher as I don't test it)

Thanks, it's getting there, but looks a bit of a mess at the moment 🙂

I think I my need to play with the flow I bit or add a spray bar a to see if that helps with the co2
 
Andy Pierce said:
8 bps is a lot for a 40 litre; I run mine at 2 bps. That said, your drop checker colour looks good and your plants look great so unless you're unhappy about some aspect of the tank (other than going through CO2 tanks quickly) I'd be tempted to just declare victory and go with what you're doing.
Click to expand...

Thanks Andy.

I don't mind going through CO2 as long as plants are healthy. What got me is as you say, it seems a lot for the size tank, which to me means that there might be an issue with the flow or something and maybe I could optimise.
 
Hi , could you be losing CO2 in your filter? If you pressurise the canister(assuming it is a canister filter) the CO2 could find a way round seals.
When you had the diffuser opposite the inflow did you still have the high bubble rate?
 
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