How important is pH? What I've learned after 25 years of reefing.

PamBrent71

Active Member
BRS Member
Interesting, were you able to measure the difference it caused in ph?
Before adding the outside air we were usually reading 7.8 to 7.9 with sort of a lot of soda ash (50ml in a 80 gallon tank, IIRC). But now we are routinely at 8 or a smidge above (8.08, 8.1). So I would say we saw a 0.2 rise in our pH and we use a LOT less soda ash. Ballpark estimate on that is that we use half or less of what we had been using. 25ml is a big dose for us now.

Even with the air pumps pushing air to the skimmer and top of the tank, I can see the impact of using the oven a lot with the windows closed because we will dip back to 7.95. You know, the old logic of "it's cold and wet so let's cook comfort food". So it was a good shift for us and has been sustained even with less soda ash, but it isn't enough to overcome very high CO2. The true test will be this coming winter when we fire up the woodstove and see what happens. We usually crack a window then, so maybe it won't be too bad (no worse than braising a chunk of meat).
 

this is me

I like turtles
BRS Member
Before adding the outside air we were usually reading 7.8 to 7.9 with sort of a lot of soda ash (50ml in a 80 gallon tank, IIRC). But now we are routinely at 8 or a smidge above (8.08, 8.1). So I would say we saw a 0.2 rise in our pH and we use a LOT less soda ash. Ballpark estimate on that is that we use half or less of what we had been using. 25ml is a big dose for us now.

I'm curious as to how that works. You use soda ash to control your PH. And this does not affect your tank alkalinity?
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PamBrent71

Active Member
BRS Member
I'm curious as to how that works. You use soda ash to control your PH. And this does not affect your tank alkalinity?

Oh, it does affect alkalinity. And that's why the pH was always a little lower than we wanted it. Adding soda ash raised alkalinity when it raised pH, so it was always a balancing act of keeping the alkalinity in a good place while trying to bring the pH up more. A common thought process was, "I wish we could add more soda ash and get the pH up to 8, but then the alkalinity will be too high so we can't." It was like being stuck in an unhappy middle place where the pH was a little lower than we wanted but we didn't want to bump the alkalinity up anymore because it was already at the upper end.

But now we keep alkalinity right at 9.3 - 10 and pH at 8-8.1. pH will bump up to 8.2 when the windows are open or drop to 7.9 if I have them closed and run the stove for awhile - it still swings but at least now we swing around a good level. It might be the sort of trick that works on a smaller scale (80 gallons total) vs a larger tank that's 200+ gallons. But so far it is working.
 

reefkeeper2

Well-Known Member
BRS Member
I used soda ash years ago but stopped because it precipitated all over my sump and plumbing. I've been using kalkwasser for many years too but even with that pH still tanked at night. My sump is in the basement where the hot water heater and furnace raise the CO2 . Getting the CO2 out of your house and fresh air in is the challenge.
 

afboundguy

Acan's are inedible candy
Staff Member
Moderator
BRS Member
2020 BRS Secret Santa
I have noticed this past year when I've actually been paying attention to my tank that when the pH is around 8.2-8.3 during the summer and 8.0-8.1 in the winter there is a big difference in coral growth.

Corals need calcium carbonate to grow (CaCO3) and they use bicarbonate (HCO3) and carbonate (CO3) that's in the water to create calcium carbonate to grow. In my opinion the corals need to expend more energy to kick off the Hydrogen atom from the bicarbonate (HCO3) when they use it make calcium carbonate as they don't need that atom and they prefer to use the carbonate (CO3) since they don't hae to waste the energy kicking out the hydrogen atom.

When the pH is higher there is less bicarbonate (HCO3) in the water so there is more available carbonate (CO3) so the corals don't have to expend the extra energy kicking out the Hydrogen molecule from the bicarbonate. So higher pH means easier for corals to grow and I can say from my experience in 20+ years of reefing with really paying attention the past year to be worth it to keep a higher pH.

I'm also able to keep the 8.2-8.3 pH range in the summer without a skimmer. I just have a HOB fuge on a reverse lighting schedule and I dose BRS 2 part...
 
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