You can not check the pH of RO/DI water, with a pH meter or a test kit. The pH, what ever
it reads, is meaningless and gives false readings, as there is basically nothing in the
water for them to respond to or measure.

"This level is by test kit and also digital probe"

1. I doubt it is both the probe ad kit. Check a fresh batch, a L or so, of seawater mix
with just tap water or distilled to see what you get.

2.What is your Alk. If you have one of those batches with a very high Alk it might be
pushing your pH up

3. There may be a spot in your tank where the calcareous substrate is dissolving, pushing
up the pH

4. Heavy algae growth can bring the pH up to 9 with no problem, as the algae can remove
the CO2, which causes an immediate shift in the pH to go up. This usually will also show a
low Alk, as the plants now feed off the CO3-- and HCO3- for their CO2 needs. It is the
reason behind Macro-Algae and FW planted tanks to use CO2 injection. Poor circulation and
gas exchange can make it worse, as the diffusion of ambient air CO2, into the tank, will
not be able to keep up with the plant demand for CO2



"The PH from your DI resin water could be high
and has basically destroyed your tanks buffering capacity over time."

There is no alk or buffering in RO/DI water, all of it has been removed. RO/DI units
automatically destroy all your "buffering capacity"



Boomer

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