I do not get this

[Randy Holmes-Farley]

This is my hypothesis. We all know that photosynthesis species produce oxygen when sun up. In a reef, this adds to dissolved oxygen to water.higher dissolved oxygen will increase ph. When lights turn off , there's a reversal of photosynthesis. This will effect ph lower. Plus corals also contribute to this process. Thus lower ph.

Now you need to determine what time of the day ph is dropping.

Dissolved O2 has no impact on pH. It is consumption of CO2 by photosynthesis that raises pH and production of CO2 by respiration that lowers pH.

 

[Randy Holmes-Farley]

One more, Lasse, if I had your ank. I would move ph meter to different locations. Bet you'll get some different readings. Just saying

In a reef tank with reasonable flow, there's not going to be a measurable pH difference between different locations, unless you measure in a place not mixing well with the water body, such as a refugium with low flow or down in sediments.

 

[Dr. Dendrostein]

One more, Lasse, bacteria maybe coating onto ph probe, may effect readings?

 

[Dr. Dendrostein]

Oh boy, I opened Pandora's box. I'm out of here. Heehee

 

[Dr. Dendrostein]

Dissolved O2 has no impact on pH. It is consumption of CO2 by photosynthesis that raises pH and production of CO2 by respiration that lowers pH.

Randy, I was praying you were taking a siesta. Nothing gets by you.

 

[Dr. Dendrostein]

Randy, I know oxygen doesn't effect ph. I just said that, see if your paying attention. We all know CO2 does

 

[Dr. Dendrostein]

GOOOOOOOOOAL Sweden. Unbelievable

 

[Dr. Dendrostein]

Yes but my PH is affected very much - seems to be much CO2 in the water - but alkalinity was going down to 8 and normally - without dosing CaCl - i will have the same swing of around 0.3 to 0.4. if I have a KH at 8

Sincerely Lasse

Ok, Lasse, I feed my dendronephthya, proprietary food I made. started this new type food.
My ph was 8.6 max by 7pm. Morning 8.0 ph. Till 11am. Sun starts to shine on outside refugium by 11am? Ph rises. I start to feed this food. My ph down to 8.3ph till about 7pm. By 11am next day 7.7ph.
I think bacteria effecting ph. Causing (guessing ) acidic conditions(co2)? Did you change or add any food? Or new type food? Just my 2 cents

 

[Dr. Dendrostein]

Hi

I thought I know most things affecting the pH in a reef aquarium with a very heavy photosynthesis - but I do not

Look at this chart. You see a daily variation of the pH depending on photosynthesis and CO2 production/consumption. From 20:00 in the evening to noon the next day I´m dosing the Core 7 3A and 3B. Around 16:00 the 19/6 I discover that I had low calcium levels - around 340 ppm. I decide to use CaCl *2 H2O in order to adjust the levels. The normal dose of core 7 (1,2 3A and 3B) continue. I dose an onetime dose directly and set one of my dosing pumps to dose 32 times a day and with a amount that will rise the Ca level with 40 ppm in 7 days. and look at the graph - what´s happen. The only change is the dosing of CaCl*2H2O. Light is the same. Can it be a fast calcification that alter the pH? Not more CO2 in the room. I have normally 400 - 800 ppm CO2 in my air - these last days - no higher than 640 ppm

Yesterday KH 8.6 - today 8. Calcium - when I discover the problem 330 - today 350 ppm


Sincerely Lasse

Also @Lasse, in you system you have DSB, but you move the water under it. I accidentally did same thing, but use gravity to move my water thru it. I was trying for a trickle filter effect, but ended up by accident a DSB. I left it alone. Helps tremendously. I wonder if that bacteria effecting ph? I'm guessing? On that.

But, in conclusion, bacteria in think, effecting ph?