The Planted Tank Forum banner
1 - 2 of 2 Posts

1 Posts
Discussion Starter · #1 ·
Back in the days, the CO2 indicator came with 4dkh solution and a PH reagent. I've noticed nowdays that most CO2 indicator set only uses a solution that comes with the kit (no 4dkh solution). You just add a couple of drops into the CO2 indicator and that's all! I'm confused...what does this mystery solution contain?

I still have my drop checker along 4dkh solution from 10 years ago. Does it go bad after all this time? Please, let me know. If it's still good then I just need to get a PH reagent which almot costs the same as a new drop checker kit.

So basically my questions are:

1. Do these solutions that come with the new drop checker kits really work by themselves without needing a 4dkh solution?
2. Does the 4dkh solution go bad after 10 years?
3. Do you use the lower or the higher range PH reagent?
4. Is there anything elseI could use instead of the PH reagent? Maybe a blue food dye?

Super Moderator
12,118 Posts
It's possible that the solution is just the 4 dkH reference solution mixed with the bromothymol blue.

For your 4 dkH reference solution, it shouldn't have gone bad, provided it did not evaporate. For the pH reagent, you should be able to find bromothymol blue at a reasonable price.

1) Depends. If they are a 4 dkH reference solution with bromothymol blue pre-mixed, then sure.
2) See above
3) You need to use bromothymol blue. This is typically in the normal range pH test kit
4) No, you need to use bromothymol blue.
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.