Few questions about nanos

[-TS-Vash]

I got a 30 gallon cube its not drilled but i have 2 tanks and will try one soon.
If i have to keep it the way it is how do i keep the co2 level low.
What i mean is i see a lot of small tanks on here with only power heads. How do you keep every thing under control with no water crashing into a sump. I have had tanks since i was 4 and saltwater on and off since 03 or 04 but i have always had 75 to 120 gallon tanks.

Atm i have a aqua clear 70 on my tank with a sponge where the water comes out so it will not make micro bubbles and splash my leds i have only a few inches off the water. I run a plastic mesh top and have a maxijet 1200 pointed at the surface to move the water + all the other power heads inside the tank.

I always thought air stones put air into tanks and hob filters or drilled tanks letting the water crash down the drains put air in the water. Makes me feel dumb to ask this since i had a 120 gallon bb sps and clam tank but i dont know how air gets into the water.

My questions are how do i keep my co2 low with my filter set up the way it is?
And i have a ph problem witch may be from my co2 level idk its 7.7 at night and 7.9 in the morning. I now add kalk to bump the ph i use to run 5 gallons every few days for my top off on my 120 but it takes so little on the smaller tank to boost the ph. Is there a better way to bump the ph then kalk?

My dkh is 10
calcium 480
mag ? no test kit atm
0 on the others.

Corals look great and i have 4 fish in there
1 snowfake clown
1 neon goby
1 six line wrasse
1 royal gramma

I just hate to add kalk 2 times a day i do it right before i go to bed then in the morning when i get up.

 

[Nano sapiens]

Air will 'get into the water' at any air/water interface. The CO2 level in the water will attempt to equalize with the CO2 level in the air. Turbulence at this boundry layer helps this equalization process.

Some rooms, especially those that are well sealed with occupants constantly exhaling CO2, have elevated CO2 levels and this can depress PH levels. Try opening the windows/doors for a while and see if the PH rises. Tanks that contain life will have variations in PH during a 24 hr period due to photosynthesis and other processes (sometimes hardly detectable, sometimes quite large).

From the WEB: CO2 forms carbonic acid when dissolved in water, because it will dissociate into H+ ions and bicarbonate ions. Carbonic acid is an acid, and acids have low pHs (below 7), so high levels of carbon dioxide will mean a low pH