What makes the ph too high?

[mjs]

Tank has been running pretty steady until recently.
Readings 75 gallon, 10 g sump
salt 1.023
Temp 80
Am 0
nit 5
Kh 11
alk 300
cal 360
phs 0

except my ph has stayed at 8.6- 8.7, and a bit of hairy algae and bubble has formed.

i do a 10- 15 gallon change every week w RO, always tested, ph is at <8.0

what causes the ph to stay up?
usually, i battle to get it to stay at 8.3

 

[wrightme43]

What kind of test kit are you using, if you dont mind.

 

[mjs]

its an Aquarium Pharma kit, but I also have a constant probe which confirms the level

 

[NaH2O]

Are you using any additives? What time of day are you experiencing the 8.6 - 8.7 result, and what is the pH first thing in the morning? When was your probe recalibrated last? Here's an article for you, if you haven't read it yet: High pH: Causes and Cures by Randy Holmes-Farley.

 

[mjs]

great article
Thanks so much

i did add some purple up two weeks ago, but other than that, just regular dkh buffer
will recalibrate, and try one of the solutions recomended

 

[steve-s]

alk 300

That'll have a lot to do with it. Ease off the purple up and be sure to test these levels (alk/Ca) before using it next time. You might want to look into a two part balanced additive instead.

As far as your current levels, a few water changes will fix that.

Cheers
Steve