• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Getting the right co2 level (starting a unit)

thevictorian

Seedling
Joined
11 Dec 2015
Messages
15
Location
bristol
Hi, sorry for such a basic question but i'm trying to get my head around co2 and every time I search for the answer I find lots of info on how to setup a co2 but not how to start one.
I've started the unit today on my 120l tank. I understand that you need a ph drop of 1 before the lights come on and that this will take a little adjusting but this is were I am unsure how much is too much so this weekend is finding the sweet spot.

Only got the unit back today and set it up as quickly as I could so it only went on about 1 hour before the lights went on.

2.40pm pH6.9 2bps (co2 on)
3.45pm pH6.8 2bps (lights on)
5.55pm pH6.6 3bps (diffuser kicking in as I didn't adjust regulator further)
6.21pm pH6.6
7.00pm pH6.5
8.00pm pH6.5
9.00pm pH6.5 (co2 off)
10.00pm pH6.5 (lights out)

The pH was measured with a pH pen and my KH is around 4. The drop checker started off blue and developed to a greeny blue when the light went out (say may have developed little further but didn't look like it had made 20ppm). I run a spraybar from a eheim external which give 10x turnover and the diffuser (2.5cm diameter with 5 coils) is on the opposite side of the tank and is producing nice fine bubbles.

So my question is about getting the level right. I've seen places suggest I shouldn't need much more than 1bps to begin with as my KH is low and the tank isn't massive, but there wasn't much of a drop in the hour before the lights went on (albeit with a diffuser that is breaking in), so how much would be recommended or where do I go next to get the best out of the system?

many thanks in advance.
 
Hi Thevictorian,

First, welcome to UKAPS :)

If you don't have fish/shrimps in the tank then you don't have to worry about too much co2.
I would suggest that you start the co2 two hours before lights on. It's very important that there is enough co2 right a the start of the photosynthesis. If you can measure the ph every 30mins before lights on, it will give you a good idea as how early you should have the co2 on. If the diffuser is slow to start giving you a good mist, maybe you should have the co2 on 2.5hours before the light...

Concerning the bubble rate, all bubble counters are different and the size of the bubbles are too. So, use the bubble rate for your information. For instance, ph is not dropping enough at 2bps, then try 3bps. But don't compare with other people bubble rates as they might not be using the same bubble counter. With one of my bubble counter at 1bps, another one gives 3bps...

The drop checker is great, try moving it around the tank to make sure you have a good co2 distribution.

Cheers,
Manu
 
Thanks for the advice and warm welcome.

There is no livestock at present as I want to get this right first. I have seen it mentioned that you want a 1 drop in ph but different sources suggest this needs to be done before the lights go on and overs seemingly say over the entire photoperiod. I have turned turned the unit on 2 hours before the lights today and am recording the parameters to see what adjustment t is needed.

Thanks again
 
Hi, another question if I may. Dialling in the co2 now and whilst I don't get a drop of 1 in the pH yet, at the end of the day the drop checker looks the same colour as the jbl one in this http://www.ukaps.org/index.php?page=co2-measurement-using-a-drop-checker (the bottom one which is described as "when there is too much co2"). Now to me it doesn't look very yellow to the eye but its a near identical colour.
As this is at the end of the day and I haven't had a whole drop of 1 pH (and yeah I know that is a guide), would it be ok to drop the bubble rate a little and not worry about the full 1 pH drop? (my KH measured at 4 but it is with a dip strip so might be higher) I have three of these drop checkers (was given three so thought i'd use them) and they are all over the tank and all reading the same, so I took that as a good even distribution of gas.

Thanks again in advance.
 
It is true that you can find many conflicting bubble counts on the forum!
It would appear that some folk can get a one point drop with a low BC but I personally suspect that the majority of us use & possibly waste lots more C02 than the lucky few!
I am probably only going to add to the conflictions, however this is my opinion... Yes get a one point drop with whatever amount of bubbles it takes.
Once you have established the desired PH drop then see if you can fine tune the flow & surface movement to achieve a lower BC count or refine the diffuser operating pressure etc.... I would think 3-4 BPS would be a good stating point but be aware all this testing should be done without fish in the tank.
 
  • Like
Reactions: tim
You should be looking at the 1 point drop at the start of the photoperiod, when plants need it most remaining steady through most of the photoperiod, not easy to master co2 well, make adjustments slowly then watch the difference for a day or two then adjust some more until your happy you have the best levels for plants and livestock, if you keep your photoperiod around 5 hours and light intensity low whilst dialling in co2 you'll have much less worries about algae Ime, hope this helps.
 
Thanks guys. The bps (again I know it varies with counter etc) is around 4 at the moment and is on 2 hours before lights come on. I only got a 0.5 drop today so have upped the bps a little and set the co2 to come on 3 hours before just to see how this changes things (i'll then try and dial it in more if I can get the drop). There are no livestock at risk and the lighting is still relatively low, plus on advice mentioned earlier I am adding a little liquid carbon before the lights come on to help prevent algae and melting.

I think I know what i'm doing now but appreciate the advice.
 
Its an eheim external, 2071 I think, which should give roughly 10x turnover. The flow uses the spray bar along the back and all the plants gently move under it. I have spiral glass diffuser with 5 spirals in it and it kicks out a good amount of fine bubbles. This is opposite the spraybar and the drop checker shows the same wherever in the tank, so thought it was a nice position for it but probably not optimal. ITs the pH drop i'm not getting so I guess I could move the diffuser near the filter inlet to see if that makes any difference and improves things?
 
Well the one point PH drop is quite a new measurement for me and I am not sure if I have always achieved that in the past.
I do aim for that now though, I use a reactor that seems to deal with fine adjustment so I can quite easily adjust my PH down.
However I use a really high bubble count to get there and to get my plants growing well, so don't be shy to turn yours up a bit more at this experimental stage.
You may find you don't need to get a full one point drop, you might see positive and fast growth with less of a drop?
 
I'm not normally obsessed with chasing numbers but finding the small adjusting quite interesting. The plants look good at the moment and i'd like to keep it that way but I have a plan of action in my head now.
 
Back
Top