Curious question on PH….have I gone too far to remove Co2?

[CreamCityCorals]

Hey y’all!

My current system is roughly 450 gallons of actual water volume heavily sps dominated. Starting in September, my SPS has not been thriving like it had been in months/years prior. Throughout 2023 I have pushed the limits of my system in regards to PH. I have run a method similar to that of Chris M at aci in regards to kalkwasser. Dosing all of my top off at night with fully saturated Kalk.

Additionally I have a lightly insulated fish room in the basement where most of the system and its components reside. That room runs a massive HRV to remove co2 and keep the air fresh. Which is does effectively. Co2 in that room stays close to ambient levels unless I am in there for long periods of time.

I run a large skimmer to outside air as well and have had to supplement alk with 2 part soda ash dosing to keep up with drmand. This was mainly done as a test to see how the system would respond at a high PH and how that would affect growth rates.

My PH bottoms out at 8.4 and gets up just below 8.6 consistently everyday.

Nutrient levels around 10 ppm are maintained with sodium nitrate dosing and po4 stays steady about .06-.08. On occasion I supplement this with small amounts of dosing, but large fish feedings typically take care of that.

Alk stays around 9.5 dkh.

My question is, is it possible that by exhausting co2 in the system to this level, I am getting to a point where organic carbon is somewhat limited and affecting the overall health of the system?

@Randy Holmes-Farley

 

[CreamCityCorals]

I should add I have checked most other buckets as multiple icp, pump checks, contaminants, water changes etc.

 

[bushdoc]

I reckon you are referring to photosynthesis (6CO2 + 6H2O → C6H12O6 + 6O2), where Carbon dioxide and water react to produce simple sugars. This process obviously produces organic carbon by zooxanthellae inside hermatypic corals in Reef Tank.
Those who run greenhouses for commertial production of plants know that raised CO2 level increases bio production.
There must be a reason why pH range around coral reefs is around 8.2-8.6. Corals also need to build their skeleton and for that CO2 have to be lower ( and pH higher).
I suppose that pH of your system is still within acceptable range, however you might keep it deviated a bit more towards the middle to avoid issues with touching extremes, so to speak.