Very high ph, 8.7

hart24601 · Aug 21, 2017

Hey Randy. This seems wild, but my pH is really high - I have always been a fan of higher pH in the 8.3 range if it was easy by running a co2 scrubber or kalk, but I recently decided that I would try running macro algae without a skimmer - so I stopped all dosing and removed the skimmer. Part of the reason I removed the skimmer was for more room and macro growth. I had a co2 scrubber on to keep the pH around 8.3 or it would drop in the 7s.

I bought a kessil h380, this thing is a beast, but is it possible the pH is really that high? I have an apex probe and a reef keeper light, I just calibrated them last night with fresh Milwaukee packets and the RLK probe (older) says 8.66 and the apex is a bit above 8.7.

My BN have bleached from the bottom up and a tubeworm which had seemed to be great for a couple months bailed out of his tube, which I have never seen before. Is this from the pH?

The sump has a powerhead in it moving water on the surface and I do have the return on the tank at the top for surface exchange. I hooked an airpump up in the sump but no real change. I had the kessil on 24/7 but now am thinking 40min on/20 off. Alk is 10dkh and no dosing for 3 days (it was 11).

Thoughts? Can macro growth really push pH that high even with an air pump going?

Randy Holmes-Farley · Aug 21, 2017

Do you have good aeration/a skimmer?

You can try the aeration test usually used to diagnose low pH issues. The pH should drop with aeration (if not, it is likely testing error). The pH should not be over about pH 8.4 with your alkalinity.

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

hart24601 · Aug 21, 2017

I recently removed the skimmer as it really wasn't pulling much from the water and took up a great deal of room. I suppose this depends greatly on surface exchange, but how long would you expect degassing of CO2 to take? I guess I could add a nano skimmer mostly for gas exchange but seems like a waste.

With both probes on two systems, apex and RKL being calibrated with single use packets (so no mixing error) showing pH above 8.6 I am doubting there is much error at this point in the measurements. I did turn the kessil off about 1hr ago and the ph has dropped to 8.52.

hart24601 · Aug 21, 2017

Oh and thank you Randy for all your help and articles over the years. You are the patron saint of reef tanks!

hart24601 · Aug 21, 2017

I added 1ml per gallon vinegar, wow that dropped pH like a rock. I also cleaned return pump for even more surface exchange and will just have to play with how long the kessil h380 is on/off to allow degassing. Randy, any idea how long photosynthesis lag time is? Aka from lights on to photosynthesis. I am wondering if a 40/20 on off. Cycle or 100 min/20 off cycle would help and still grow macro?

This h380 is a quite the light.

Randy Holmes-Farley · Aug 22, 2017

hart24601 said:
I recently removed the skimmer as it really wasn't pulling much from the water and took up a great deal of room. I suppose this depends greatly on surface exchange, but how long would you expect degassing of CO2 to take? I guess I could add a nano skimmer mostly for gas exchange but seems like a waste.

With both probes on two systems, apex and RKL being calibrated with single use packets (so no mixing error) showing pH above 8.6 I am doubting there is much error at this point in the measurements. I did turn the kessil off about 1hr ago and the ph has dropped to 8.52.

When I experimented with my system by removing my skimmer, the pH rose too high due to limewater use, and I returned it to service. IMO, aeration is one of, if not the main benefit of a skimmer.

hart24601 · Aug 22, 2017

I might just have to add one back solely for that purpose. Maybe I can find a small one that doesn't take up much space. Just never thought I would have a too high pH problem...