If you have BBA, you need to describe each aspect of the CO2 system, not just the data from one reading or a DC reading.
While they are useful, they have a long lag time and color reading is tough for many.

I think the water is your asrea should be fairly good as far as KH, so the pH meter would give you better responsive results more than likely.

Also, by the time you measure the CO2, after BBa is there, you may have corrected the issue.

BBA generally will not go away on it's own, however, you can stop new growth or add Excel and manual cleaning/trimming to get rid of the stuff that remains.

While manuy seem bedeviled and in disbelief with CO2 and BBA, it really is solely a CO2 issue, no matter how many folks claim it's something else, they generally have not looked at the their CO2 close enough if they believe this.

I've never once been able to induce BBA with anything else suggested.
Until that day, I'll stick with CO2.

I've also cured every BBA issue going back 15 years using nothing more than CO2.
I spent 3 years messing with BBA, Steve and I talked a lot and spent a long time figuring it out to be sure.

If you have BBA, you will believe anything if simply adding a little bit more CO2 did not seem to resolve things for you.

Some limited PO4, but that decreases photosynthesis, which in turn also limits CO2 uptake and thus demand.

So now you do not need to add CO2, you are now PO4 limited, not CO2 limited at that point.

This example is classic myth/pitfall of equating correlation to cause.
Getting good stable CO2 is 90-95% of this hobby if you use CO2 gas.

Never underestimate it and think you know it all when it comes to CO2.
Only a fool would do that.
I've been a fool a lot in the past on that one.
Now I know better and give CO2 the respect it demands.

Regards,
Tom Barr