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Help needed for Co2 Profile

swackett

Member
Joined
29 May 2008
Messages
449
Location
Surrey
Hi,

I'm trying to get the co2 in my tank stable during lighting period, I've borrowed a ph pen and have charted morning, co2 on, lights on, co2 off lights off on a chart.

Looking at the chart my co2 builds over the lighting period before returning to normal ph for my water over night.

My Questions are
  1. Should I be trying to aim for ph 6.9 during the lighting period based on my water kh?
  2. It takes 4 hours to get to target ph level, therefore should I change the co2 start time to 12:00 or something else I've been reading is increase surface agitation and increase co2 injection rate to gain equilibrium quicker?

Tank setup details are
  • 125L
  • Pressurised co2 injection @ 1bps
  • water ph 7.4
  • water kh 7
  • water gh 11
  • some surface agitation
    co_profile.jpg
 
Forgot to mention gas on at 13:30 and lights on at 16:00 (the 14:00 on the chart should be 13:30)
 
Surface agitation increases CO2 loss so best trying to decrease it during CO2 injection.
Measuring pH is a rough guide going off drop checker is better but colour change is slow.
I use pH controller say set to 0.8pH drop when it got to target pH watching fish OFC wait 2hrs then check drop checker to see colour change. Then adjust target pH rinse repeat next day.

Obviously having pH controller makes it easier Adjusting the BBS rate.

Takes time to get it right. Chatting with another much experienced scaper who advised me it took them a couple off months to get it right. Think they was Adjusting their BBS rate mainly at weekends so they could keep an eye on their fish.


Sent from Mountolympus via neural interface
 
Surface agitation increases CO2 loss so best trying to decrease it during CO2 injection.
Measuring pH is a rough guide going off drop checker is better but colour change is slow.
I use pH controller say set to 0.8pH drop when it got to target pH watching fish OFC wait 2hrs then check drop checker to see colour change. Then adjust target pH rinse repeat next day.

Obviously having pH controller makes it easier Adjusting the BBS rate.

Takes time to get it right. Chatting with another much experienced scaper who advised me it took them a couple off months to get it right. Think they was Adjusting their BBS rate mainly at weekends so they could keep an eye on their fish.


Sent from Mountolympus via neural interface

Yes thanks, during the week I'm leaving it unchanged, tested yesterday evening and PH down to 6.85, which according to the link I found on here to RotalaButterlfy is spot on 30ppm. Now I guess i need to get it to 6.85 for lights on and keep it there for the lighting period.

I may experiment at the weekend with upping bps to 2 and increasing surface agitation to see if I can get the ph lower quicker at the same time as keeping it constant by the fact the surface agitation is degassing at an increased rate.
 
I do find getting the first 0.5pH drop is very fast, but as the water becomes more saturated with CO2 each 0.1pH change tanks longer and longer, law of diminishing returns OFC. Plus the morning pH varies in the tank esp after WC. but when target pH reached I do constantly have the drop checker a faint yellow.

As for my duel CO2 injection rate, well its way to fast to count on both input lines, even when its been on for some times- the joys of a 500L tank, Glad I got the pH controller as getting the BBS right would off been very time consuming, plus dont have to worry about to high [CO2] if BBS set too high as it just switches off at target pH
 
I do find getting the first 0.5pH drop is very fast, but as the water becomes more saturated with CO2 each 0.1pH change tanks longer and longer, law of diminishing returns OFC. Plus the morning pH varies in the tank esp after WC. but when target pH reached I do constantly have the drop checker a faint yellow.

As for my duel CO2 injection rate, well its way to fast to count on both input lines, even when its been on for some times- the joys of a 500L tank, Glad I got the pH controller as getting the BBS right would off been very time consuming, plus dont have to worry about to high [CO2] if BBS set too high as it just switches off at target pH
So I may experiment with a higher bps rate to see how quickly the pH drops as without a pH controller I'll need to manually monitor during the light period.

Sent from my SM-G935F using Tapatalk
 
So is this profile good or bad? If it's bad any suggestions on how to improve it?

Thanks
 
Hi
I would try and get the Ph down to a least 6.8 before lighting comes on!
Up the bubble rate for the 2.5 hours before lights come on....you need to be vigilant if you have fish or critters in the aquarium!
A couple of Co2 drop checkers would be a asset.....distributed at different ends of the aquarium!

My observations below!
Strangely enough if you have floating plants the Ph drop will be quicker as they hold the gas in situ over a longer period time...plus they also the tend to keep the Ph from dropping too much overnight!
 
Hi
I would try and get the Ph down to a least 6.8 before lighting comes on!
Up the bubble rate for the 2.5 hours before lights come on....you need to be vigilant if you have fish or critters in the aquarium!
A couple of Co2 drop checkers would be a asset.....distributed at different ends of the aquarium!

My observations below!
Strangely enough if you have floating plants the Ph drop will be quicker as they hold the gas in situ over a longer period time...plus they also the tend to keep the Ph from dropping too much overnight!

The other day I left our tap water for 24 hours and then tested the ph, the reading from the tap was 7.4 and after 24 hours it was 8.2, however the KH is still 7 so I'm still aiming for 6.8 - Is that right?

Yesterday I upped the co2 to 2 bps and increased surface agitation, the ph drop was quicker, down from 7.4 to 6.9 in 1 and 1/2 hours and it stabilised at 6.79 until lights out at 10pm. I'll try starting the co2 at 14:00 today with lights on at 16:00 to see how I get on.
 
Hi
Have you read the below article from Clive!
https://www.ukaps.org/index.php?page=co2-measurement-using-a-drop-checker
6.8 is good!
Your going in the right direction, Co2 needs small adjustments if your not familiar with this side of the hobby!

Thanks for the link, I think I may have read that a few years back, I joined here in 2008 and had varying success with a 240l, 70l and 125l. After a few years off I'm just trying to get my head back around the process and anything that may have changed (LED lights for example) since I was last here.
 
I wouldn't get too bogged down with the numbers. The numbers are an ideal and all the tests available don't really work to the same accuracy as the numbers. I think stability is more important than the exact numbers involved which may or may not be right. I've been messing with my co2 lately. I was having problems with surface scum which meant my tank didn't breath properly. It pretty much held co2 all of the time even through the night and my bps rate was quite low and drop checkers always somewhere between lime green and yellow. Since adding a surface skimmer I get better gas exchange, dc is now dark blue in the morning. The downside if you want to call it that is the amount of gas I need to pump in to achieve a green DC, not sure of the exact amount but I've went from 2/3 bps to uncountable, near on a constant flow of bubbles.

The upside of this is my tank appears to be a lot healthier and I'm sure the fish and plants appreciate it over night and the water a lot clearer with elevated o2 I guess. I don't get the same colour DC though which these days is just plain old sort of 6.5 green. In effect the tank looks a whole lot better with slightly less dissolved co2.

I guess my point is if your plants are thriving and no signs of any co2 related issues then it maybe best to try and hold it there and keep it steady. 30ppm co2 is a bit like EI dosing in so far as you just need to make sure there is enough and it's well circulated around the plants. Other than that the plants aren't that fussed about what your ph pen or DC is saying.
 
I wouldn't get too bogged down with the numbers. The numbers are an ideal and all the tests available don't really work to the same accuracy as the numbers. I think stability is more important than the exact numbers involved which may or may not be right. I've been messing with my co2 lately. I was having problems with surface scum which meant my tank didn't breath properly. It pretty much held co2 all of the time even through the night and my bps rate was quite low and drop checkers always somewhere between lime green and yellow. Since adding a surface skimmer I get better gas exchange, dc is now dark blue in the morning. The downside if you want to call it that is the amount of gas I need to pump in to achieve a green DC, not sure of the exact amount but I've went from 2/3 bps to uncountable, near on a constant flow of bubbles.

The upside of this is my tank appears to be a lot healthier and I'm sure the fish and plants appreciate it over night and the water a lot clearer with elevated o2 I guess. I don't get the same colour DC though which these days is just plain old sort of 6.5 green. In effect the tank looks a whole lot better with slightly less dissolved co2.

I guess my point is if your plants are thriving and no signs of any co2 related issues then it maybe best to try and hold it there and keep it steady. 30ppm co2 is a bit like EI dosing in so far as you just need to make sure there is enough and it's well circulated around the plants. Other than that the plants aren't that fussed about what your ph pen or DC is saying.

Thanks for the reply, the Staurogyne is losing its bottom leaves, and some leaves now appear translucent. I'll update my journal shortly with a few photos. :)
 
OK buddy, I follow you journal so I'll check it out. If you haven't got a drop checker I would definitely invest in one , for what they cost they are an excellent investment. I like you spent a lot of time doing a maths exams when what I actually needed to do was start listening to the plants. The DC is there now more as an early warning system that I don't have any leaks or issues in the set up. If I glance over and see its green during the lighting period I just accept there's enough co2 unless the plants tell me anything different.

Sent from my STH100-2 using Tapatalk
 
I had some surface scum with lower surface agitation, bps at 1.3 and at this rate it took about 4 hours to go from 7.4 to 6.8 before lights on. So this weekend I upped the co2 to 2bps and increased surface agitation, pH at 7.6 before lights on and 6.9 when lights on. Decreased gap between co2 and lights on to 2 hours.
 
Surface agitation and surface scum makes a huge difference to your injection. Now I have no scum I can pretty much gauge where I need to be, when the scum was there it was up and down like a yo yo.

Sent from my STH100-2 using Tapatalk
 
Surface agitation and surface scum makes a huge difference to your injection. Now I have no scum I can pretty much gauge where I need to be, when the scum was there it was up and down like a yo yo.

Sent from my STH100-2 using Tapatalk

Higher agitation seems to have fixed surface scum and the co2 now gets to correct level by lights on. Now just to keep the plants healthy
 
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