Why would kalkwasser raise ph in one tank and not another, both tanks in the same home

[ddc0715]

bare with me i will try to be detailed but short. hahaha, I have two tanks a 220 fowler with a few softies and 1 Stoney and a 150 mixed reef.
in my journey to understand how to raise ph. i determined that co2 is my emeny. on my mixed reef, i did the following
1. installed a scrubber no real WOW change in ph still 7.8-7.9. i removed the scrubber
2. ran my skimmer to outside air, again no real wow change
3. added some air stones to the sump using inside air, got about a .1-.2 bump now 7.9-8.1
4. installed a ceiling fan in the fish room with a fan blowing across the top of the tank again no change in ph
5 researched the craps out of c02 entering tank determine that kalk would be best to try for two reasons, stability and it co2 using properties.

I monitored my evap rate for a few days and determined that both tanks go thru about 1-1.5 g a day. so I mixed up some kalk at 2 teaspoons per gallon. built a kalk reservoir to aid in keeping settlement out of my ato . I mix it in that, then drain into jugs and then add to the ato.

First I dripped into my 150. i saw no change in ph. so I stopped the drip method and started adding to the atos of both tanks. i clearly see an increase in ph on my 220 fowlers 8-8.2 but there is still very little movement in my mixed reef tank ph. I'm up to 7 still -8.1 both tanks are in the same home..... any ideas? why one tank is doing well with kalk and the other is not????? I'm pondering a much larger skimmer for the 150 I'm presently running a bubble mag curve 7. pic 1 is my 150

 

[blaxsun]

They’re both still relatively good pH results.

 

[arking_mark]

1 and 2 probably indicate that your shimmer doesn't outcompete the other aeration your tank gets.

3 may indicate that your tank is under-aerated.

I wouldn't expect 4 to have much effect.

With saturated kalk, you can calculate expected pH impact. Generally speaking, on average, you should expect roughly a 0.1 pH bump when dosing to evaporation rate. The more noticable bump in the 220 again may be due to insufficient aeration.

Insufficient aeration just means that the tank will be slower to equalize with the air. Hence it can accumulate CO2 from your livestock and depress pH. Additionally, it will be slower to equalized the OH- from the kalk with the higher CO2 air.