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Drop checker / PH values not aligning

ChrisMachell

New Member
Joined
5 Nov 2020
Messages
19
Location
Brighton
Hi all,

I've been having a hard time getting my drop checkers to turn fully green, usually hovering around the turquoise colour (I have one at either end of the tank, both reading the same). I have a 240l, moderately planted tank, inline diffuser (canister) and an internal filter at the other end of the tank which provides good flow. Micro bubbles are visible everywhere in the tank. However, my PH is currently reading around 6.8-7.0 (hard to tell with the API kit) with a dKh of 10.5 - which is odd as this would suggest a high level of CO2 in the water column. It also scared me a bit as I obviously don't want to gas my fish (no signs of distress but airing on the side of caution). What do you think is more likely - my drop checker solution is bust, my PH solution faulty or do I need an eye test?

Attached is a photo of the drop checker nearest the outflow (please excuse the algae, I'm working on it!)

Thanks!
20211006_151257.jpg
 

John q

Member
Joined
6 Jan 2021
Messages
1,154
Location
Lancashire
However, my PH is currently reading around 6.8-7.0 (hard to tell with the API kit) with a dKh of 10.5 - which is odd as this would suggest a high level of CO2
Hiya mate, I wouldn't pay that much attention to the Ph-kh-co2 tables, these can be notoriously inaccurate, what is important is your ph drop.

You need to find the ph of off gassed tank water first, you can do this by leaving some tank water in a glass for 24hrs and then take the ph of that. From that reading you're then aiming for a 1 ph drop. For example if off gassed tank water is 7.5 then you'd be aiming for it to drop to 6.5 when you add co2 in the tank.
If you're getting a 1 ph drop then your drop checker should turn green, if it isn't then the solution could be suspect.
 
Last edited:

ChrisMachell

New Member
Thread starter
Joined
5 Nov 2020
Messages
19
Location
Brighton
Hiya mate, I wouldn't pay that much attention to the Ph-kh-co2 tables, these can be notoriously inaccurate, what is important is your ph drop.

You need to find the ph of off gassed tank water first, you can do this by leaving some tank water in a glass for 24hrs and then take the ph of that. From that reading you're then aiming for a 1 ph drop. For example if off gassed tank water is 7.5 then you'd be aiming for it to drop to 6.5 when you add co2 in the tank.
If your getting a 1 ph drop then you're drop checker should turn green, if it isn't then the solution could be suspect.
Ah, nice one, cheers buddy. I will try this and see where we are. I mean, I've got decent growth, the fish seem fine, and as I said visible bubbles all over. But the paranoia has creeped in that I must be doing something, anything wrong!
 

ChrisMachell

New Member
Thread starter
Joined
5 Nov 2020
Messages
19
Location
Brighton
Hi all,

I've been having a hard time getting my drop checkers to turn fully green, usually hovering around the turquoise colour (I have one at either end of the tank, both reading the same). I have a 240l, moderately planted tank, inline diffuser (canister) and an internal filter at the other end of the tank which provides good flow. Micro bubbles are visible everywhere in the tank. However, my PH is currently reading around 6.8-7.0 (hard to tell with the API kit) with a dKh of 10.5 - which is odd as this would suggest a high level of CO2 in the water column. It also scared me a bit as I obviously don't want to gas my fish (no signs of distress but airing on the side of caution). What do you think is more likely - my drop checker solution is bust, my PH solution faulty or do I need an eye test?

Attached is a photo of the drop checker nearest the outflow (please excuse the algae, I'm working on it!)

Thanks!
View attachment 175138
Update: No sooner did you provide your great advice than my farther-most DC turned the greenest it's ever been! I swear I did nothing and it just turned on its own accord. Clearly it was just waiting for me to lose my patience and turn to the forums 🤣. Thanks for your advice, @John q and @GHNelson , I'll keep it in mind for the future 👍.
 

ian_m

Global Moderator
UKAPS Team
Joined
25 Jan 2012
Messages
5,330
Location
Eastleigh
Put you test kit in the bin, as you have seen can only be relied on to transfer money from your wallet to the shops, which they achieve 100%.
What about Test Kits ?

An in tank drop checker is the best, albeit slow (1/2 hour ?), way to determine tank CO2 levels.

If you insist on knowing your tanks pH (so you can use the highly misleading CO2 ppm vs pH charts) then a pH pen is much better than a liquid/strip test kit as not affected so much by other ions/salts/organics in the water.

As you see even at this level of "green drop checker" the fish are fine. The reason your drop checker is not changing is low CO2 levels and/or poor flow/distribution.
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