• 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

Co2 test reagent ??

Frenchi

Frenchi

Member
Joined
15 Jan 2014
Messages
671
Location
West Yorkshire
Hi ppl
I've been using jbl test liquid now since I started planted tanks, it is very good and clear to see in the little viewer it comes with, I did try some other brand liquid but it doesn't show up very well when it changes colour, it's very weak..
Can you guys recommend a good strong coloured liquid please

Thanks


Sent from my iPhone using Tapatalk
 
its just 4dkh solution with bromothymol blue in it. Can't imagine JBL are doing anything magical other than adding more of the blue! Could just mix your own?
 
I see ok maybe worth mixing my own then is it easy or is there a strategy??


Sent from my iPhone using Tapatalk
 
don't think so, just add some drops of blue to the 4dkh til it looks like the JBL stuff you liked. You can buy both separately. I think you can also make your own 4dkh, but because you have to be quite accurate you end up either having to make more than you'd ever need, or needing ridiculously expensive scales.

To be honest, I can't really see a problem in the first place! Even the expensive stuff is cheap, considering how little you use. I'm aware some people change it weekly, but I don't think there's actually any benefit (except to JBL...) in doing it that regularly.
 
Thank you .. It always helps :) I got a bottle of ready mixed from co2 art but it was a bit weAk and hard to see the reading.. I have just ordered some bromothymol blue from them to add a bit of extra colour .. Hopefully that will work:)


Sent from my iPhone using Tapatalk
 
Hi all,
naughtymoose said:
12g NaHCO3 in 1litre of RO water
Click to expand...
That is the stock solution (400dKH).

You need to dilute this stock solution 1 in 100 to give you the 4dKH (and add bromothymol blue) solution. You can do it all by weight, so 10g of stock solution and 990g RO water will make a litre of 4 dKH solution.

cheers Darrel
 
I haven't used the (professional) 4dkh fluid yet, i made my own. When i look at the instructions of say Cal Aqua Labs then it turns blue when you put in Bromothymol. But in my 4 dkh water it turns green straight away. I guess it's the PH value of the fluid doing that and it must be 7,5 at least to turn blue.

I wonder what should be the best Ph value of a home made fluid? Did anyone ever put a PH meter in the bought 4 dkh fluid? Does it even have effect on the reading when the ph value of the fluid is in an other range?
 
If you mix the bromo blue with the 4dkh solution in the dc, is this not making the 4dkh solution more diluted? I dont know why I never thought of this but this can have a big impact on co2 levels. Make any sense?
 
I have always used the jbl and it's a very good indicator but when I tried others it just didn't colour up the Same .. Strange this one ??


Sent from my iPhone using Tapatalk
 
Just to piggyback on this one, do you really need to change the reagent each time you do a water change (as ceg suggests in his "measuring CO2 using a dropchecker" article)?

Does the stuff expire / lose its potency or something?
 
Its actauly simple physics, the (moist) vapor of your aquarium water goes in the dropchecker and reacts with the fluid in there and obviously the fluid in the dropchecker vaporises as well so it will exchange some.. I guess over time the fluid will get diluted, this is all in very small amounts but still logic. I got a hangon dropchecker and it clearly shows condensation in there. Since the fluid is just a mild indicater which is always 2 hours late, it's just a simple checker to give you a warning, i guess a permanent PH checker is more direct and more acurate. I use both, i just like the fancy look of the drop checker..

4 dkh water in a closed bottle will stay 4 dkh for ages. Like a bottle of demi water stays demi water as long as you don't put something in there it will never expire.
 
Last edited:
Hi all,
zozo said:
But in my 4 dkh water it turns green straight away. I guess it's the PH value of the fluid doing that and it must be 7,5 at least to turn blue.
Click to expand...
That is strange. Bromothymol blue is just a narrow range pH indicator. Assuming you've used RO water to make up your 4 dKH solution, the pH should be pH~8.

I might be tempted to get some new bromothymol blue.

The reason for the known pH value is that the bicarbonate ion (HCO3-) is in equilibrium with with the H+ ion from H2CO3 (carbonic acid from CO2). At atmospheric CO2 levels (~400ppm), the equilibrium pH value is ~pH8.

There is more explanation here <"pH drop and high alkalinity">.

cheers Darrel
 
dw1305 said:
That is strange. Bromothymol blue is just a narrow range pH indicator. Assuming you've used RO water to make up your 4 dKH solution, the pH should be pH~8.
Click to expand...

I have seen some chinese bromo or whatever it might be which is a dark green colour, not blue. It will turn into a light green/yello colour once co2 gets in there. So for practical purposes its the same as just the blue one. The change in colour is still quite obvious. Sorry maybe not chinese, just another product:).
 
dw1305 said:
Hi all, That is strange. Bromothymol blue is just a narrow range pH indicator. Assuming you've used RO water to make up your 4 dKH solution, the pH should be pH~8.

I might be tempted to get some new bromothymol blue.

The reason for the known pH value is that the bicarbonate ion (HCO3-) is in equilibrium with with the H+ ion from H2CO3 (carbonic acid from CO2). At atmospheric CO2 levels (~400ppm), the equilibrium pH value is ~pH8.

There is more explanation here <"pH drop and high alkalinity">.

cheers Darrel
Click to expand...

Thanks Darrel, i guess i get me some new bromothymol, mine is always at least 1 point off the real Ph value. Got 2 elektronic testers 1 permanent and 1 pocket tester. Both give the same value, lets say 7 and when i test the same water with the Bromo it says somewath like 6. Very inacurate reading. Ill try an other one, just to see what happens. I used a bottle of regular Demi water to make the 4 dkh but the Ph value is somewhat 7, so i possibly did something wrong, i do it over again.
 
luckyjim said:
Does the stuff expire / lose its potency or something?
Click to expand...
Yes it gets degraded by light. Lasts longer in things like the JBL drop checker (the one in Geg's DC article) than in plain glass drop checker.

Jose said:
If you mix the bromo blue with the 4dkh solution in the dc, is this not making the 4dkh solution more diluted
Click to expand...
No, generally the bromo blue is supplied slightly diluted already with 4dKH water. As long as you only dilute using 4dKH water you are OK.
 
You must log in or register to reply here.
Back
Top