PH ? - Liquid test kit vs ph meter
Here's the stats:
RO/DI water, KH by potassium carbonate/snail shells, GH by Seachem Replenish. (switching to GLA GH booster in the near future.)
TDS out of the RO/DI is 0ppm, checked with two TDS meters.
KH is 3
GH is 4-5
No CO2 injection, yet.
Two india almond leaves in tank.
Now onto my question.
When I check the pH with my calibrated meter I get a pH of ~6-6.2, doesn't mater what time of day.
When I check the pH with the API kit I get ~7.0-7.2.
I check both samples together.
What I do:
I keep the meter in the standard solution which is pH 7.0, I kick on the meter before pulling it out of solution and it always reads 7.0.
I then rinse the meter and API glass tube in RO/DI water, then rinse in aquarium water. Dump all that out.
I then extract water from the tank, put it in the glass container rinsed by RO/DI-aquarium water, stick the pH meter in, swirl water with it, and then take the 5ml of water out for the API test.
So I'm watching my meter as I put drops into the tube and shake.
The test drops are of recent manufacture and don't expire for a long long time.
Why are they different and which one is it?
Thanks in advance!
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