[saddletramp]

Advice, please!
Just calibrated a new Hanna tester with standard solutions. Everything went smoothly.
So, I go and test the tanks which has not been done in ages. These tanks have only emerged Crypts! There are about 170 plants most doing very well. The starting water was 4 parts RO / 1 part tap water pH 7.8
To my surprise, 4 of the tanks tested pH ~ 8.3. That included a 125 gal blackwater set up.
The TDS was ~ 1150 ppm!!! The blackwater tank showed 550 ppm.
When the tester was put into RO water, it tested pH of 6.85 with 1 ppm.
I won't go into the rest of the details, but something seems radically wrong. Could the tester be defective?
Any ideas? Thanks in advance.
Bill

 

[tanan]

Blackwater doesnt mean there is very less total dissolved solid. Blackwater actually have a lot of dissolved organic compounds and tannins. Also if those tanks are run on total Diana walstad's nature style tanks. The tds and ph seems pretty normal to me.

 

[Positron]

The TDS could definitely be true as stated by Tannis, due mostly to well...tannins, and other dissolved organic compounds. If you inject co2 then some acid may be allowed to react with rocks to get even more TDS.

What I'm a little wierded out about is the high PH. You should test the kH and see what's up with that. If the KH is low then you probably have hydroxides or something in there. If it's high then it's probably just dissolved carbonates from rocks and substrate.

If it was me I would do a 75% water change with straight RO water to get the TDS down to freshwater