CO2 present in the morning

[jaypeecee]

Thanks for the link. I'm not sure I'll ever find one that costs less than £20
It seems my package is not moving at all, I decided to buy a new digital ph device to get some measurements. Calibrated it and started testing a few hours ago:
Before CO2 = 7.22 Ph
1 hr = 6.77
2 hr = 6.58 (lights on).

With a KH of 4 this puts me at 31 ppm CO2 after 2 hours (and 7 ppm to start with). Since my KH is dropping fast in the new setup, I need further testing / tweaking CO2 the next couple of weeks / months.
Will keep testing the rest of the day, and crank it up a bit tomorrow

Hi @kilnakorr

Thanks for the update.

Some people have paid less than £20 from eBay. But then run into inaccuracies, etc. I'd be interested in knowing which manufacturer and model number you chose. But, obviously, if you'd rather not say, then no problem.

So, you now have some measurements. I would suggest that 31 ppm CO2 after 2 hours is pretty good. You'll no doubt be aware that the well-known KH/pH/CO2 table is not 100% accurate. That's because other ions and compounds affect the water chemistry. I'll be interested to know at what level the CO2 stabilized with lights on.

Having new soil in tank so kh/ph is not an option as this would read 200-300ppm co2.

What happened about the CO2 from the soil substrate? How did you derive the figure of 200-300ppm CO2?

Is your water KH reasonably stable now and what figure(s) are you seeing?

JPC

 

[kilnakorr]

Hey @jaypeecee

It's not that I won't tell you the brand of ph-probe. It's just not posdible as it's not mentioned or visible anywhere which is why I mentioned it being some cheap chinese thing -£28.

The 200-300 ppm CO2 would be from the KH/PH/CO2 relation chart.

I do however think the green dropchecker in the morning was due to more trapped gasses in the soil from the first water added to the tank. As my KH is still dropping the CO2 from that reaction has no problem leaving the tank at same rate.

The rest of the measurements today:

3 hr = 6.58
4 hr = 6.50
6 hr = 6.50
8 hr = 6.51 (lights off).

seems 6.5 is where the curve flatlines at my current injection rate. This should mean a concentration of 40 ppm CO2. However, my start would also be 7.xx ppm CO2, which I believe is false. At this point, the new soil is having to much an impact of PH and KH to be useful in estimating CO2 concentration.

KH are not stable. Tap water KH is 12, and tank is 4, so quite a drop in a few days.

Will do a 50% waterchange tomorrow and check PH/KH after being mixed for a while. Then a new day of testing PH

 

[jaypeecee]

At this point, the new soil is having to much an impact of PH and KH to be useful in estimating CO2 concentration.

KH are not stable. Tap water KH is 12, and tank is 4, so quite a drop in a few days.

Hi @kilnakorr

Which soil are you using? Do the instructions advise that this soil may have an impact on pH and KH?

JPC

 

[kilnakorr]

Hi @kilnakorr

Which soil are you using? Do the instructions advise that this soil may have an impact on pH and KH?

JPC

I use Tropica Soil. Yes, does say it lowers PH and to do frequent water changes the first weeks.
Been using this stuff for years, just couldn't remember it lowering KH also.

Let's say this problem is solved. Next problem is getting my reactor setup to work properly, without the need for a larger canister filter

 

[Wookii]

Just to give you another data point, it takes my tank around 12 hours for CO2 to dissipate and the Ph to return to non-CO2 levels. I run a skimmer 24/7 also.

 

[kilnakorr]

Just to give you another data point, it takes my tank around 12 hours for CO2 to dissipate and the Ph to return to non-CO2 levels. I run a skimmer 24/7 also.

Thanks for the input. This has been resolved

 

[nigel bentley]

It’s perfectly normal. Unless you have very vigorous surface agitation, there will still be some CO₂ left over from the previous day’s injection. This is a good thing, because it means you don’t have to start injecting CO₂ quite as early before the next lighting period. Your fish won’t care, provided the CO₂ level is reasonable and there is a good oxygen level. My drop checker doesn’t show pure blue in the morning; it’s usually a dark bluish-green.

Hi Mike, Reference the surface agitation, I have an Eheim air pump running from lights off, until 7.30 am. This around 10 hours of the air pump running. Is it possible, I'm having too much agitation during the night as Dc is dark blue in the morning?
Thanks Nigel

 

[Dr Mike Oxgreen]

Hi Mike, Reference the surface agitation, I have an Eheim air pump running from lights off, until 7.30 am. This around 10 hours of the air pump running. Is it possible, I'm having too much agitation during the night as Dc is dark blue in the morning?
Thanks Nigel

Since I posted above, I have actually discovered that having overnight aeration makes my ember tetras much more active and confident during the daytime photoperiod (when the air pump is off). Have a look at the “Why are my ember tetras so shy” thread. I’ve learnt that a heavily planted tank can get low on oxygen overnight because the plants are oxygen consumers when they’re not photosynthesising, and this effect is far greater than I realised.

So my aeration comes on a few hours after lights off, and runs until the CO₂ comes on the next day. Obviously you don’t want aeration at the same time as CO₂ because you’ll just be out-gassing the CO₂ that you’re adding.

And of course, now that I’m using overnight aeration, my CO₂ drop checker is much bluer in the morning - as you’d expect. But it just about reaches a medium green by the time the lights come on, and is light green within an hour or so after.

So I now think that overnight aeration is a good idea.

 

[nigel bentley]

Since I posted above, I have actually discovered that having overnight aeration makes my ember tetras much more active and confident during the daytime photoperiod (when the air pump is off). Have a look at the “Why are my ember tetras so shy” thread. I’ve learnt that a heavily planted tank can get low on oxygen overnight because the plants are oxygen consumers when they’re not photosynthesising, and this effect is far greater than I realised.

So my aeration comes on a few hours after lights off, and runs until the CO₂ comes on the next day. Obviously you don’t want aeration at the same time as CO₂ because you’ll just be out-gassing the CO₂ that you’re adding.

And of course, now that I’m using overnight aeration, my CO₂ drop checker is much bluer in the morning - as you’d expect. But it just about reaches a medium green by the time the lights come on, and is light green within an hour or so after.

So I now think that overnight aeration is a good idea.

Hi Mike, Thanks for your thoughts, I think I will stick with aeration time as I also have tetras. I just wanted to make sure I wasn't overdoing it. Thanks Nigel