High pH, Low Alkalinity

bcarl77 · Jan 20, 2019

Hi Guys!

Recently moved from an apartment to a house and have developed a high pH problem (8.5). Historically it has always been low so I was running my skimmer through Co2 absorbing media. Before I moved (~1 month ago) I was dosing roughly 2 TSP/2.5gal of Kalk in my ATO. This would hold my alk right around 8 and pH around 8.3.

I noticed my zoanthids starting to look unhappy and start to close (all LPS are looking good). I measured my KH today and it was 5.8. For now I stopped running the skimmer and increased the Kalk in my ATO. Calcium came in a bit low at 400ppm. Any recommendations on how I can increase alkalinity without impacting my pH?

Dr. Dendrostein · Jan 20, 2019

bcarl77 said:
Hi Guys!

Recently moved from an apartment to a house and have developed a high pH problem (8.5). Historically it has always been low so I was running my skimmer through Co2 absorbing media. Before I moved (~1 month ago) I was dosing roughly 2 TSP/2.5gal of Kalk in my ATO. This would hold my alk right around 8 and pH around 8.3.

I noticed my zoanthids starting to look unhappy and start to close (all LPS are looking good). I measured my KH today and it was 5.8. For now I stopped running the skimmer and increased the Kalk in my ATO. Calcium came in a bit low at 400ppm. Any recommendations on how I can increase alkalinity without impacting my pH?

They go hand and hand. Like to know what others think. Sorry

bcarl77 · Jan 20, 2019

I know [emoji58]. Never thought I would be complaining about too high of a pH either.

bcarl77 · Jan 21, 2019

Anyone?? pH is up to 8.65 at the moment...

dougers31 · Jan 21, 2019

How are you testing??

dougers31 · Jan 21, 2019

bcarl77 said:
Hi Guys!

Recently moved from an apartment to a house and have developed a high pH problem (8.5). Historically it has always been low so I was running my skimmer through Co2 absorbing media. Before I moved (~1 month ago) I was dosing roughly 2 TSP/2.5gal of Kalk in my ATO. This would hold my alk right around 8 and pH around 8.3.

I noticed my zoanthids starting to look unhappy and start to close (all LPS are looking good). I measured my KH today and it was 5.8. For now I stopped running the skimmer and increased the Kalk in my ATO. Calcium came in a bit low at 400ppm. Any recommendations on how I can increase alkalinity without impacting my pH?

I believe you can use baking soda to raise alk without raising ph. Soda ash however will raise both.

bcarl77 · Jan 21, 2019

I calibrated my apex pH probe twice and used a separate pH pen that I calibrated as well. That was my first reaction too....

dougers31 · Jan 21, 2019

bcarl77 said:
I calibrated my apex pH probe twice and used a separate pH pen that I calibrated as well. That was my first reaction too....

Could you alk test be off? Very strange numbers...

bcarl77 · Jan 21, 2019

Measured 6.3 with Hanna checker and approximately 6.7 with Red Sea. At what point should I be concerned with the pH max?

miniChou · Jan 21, 2019

You can use two part to increase Alk/Cal levels. Although with a pH of 8.65 I would recommend taking your CO2 scrubber offline. 8.3 pH is usually what is desirable. As your pH comes down your Alk should come back up.

jda · Jan 21, 2019

Baking soda (sodium bicarbonate) will raise your alk and only have a momentary impact on pH. Washing Soda (sodium carbonate) will not impact the pH at all.

The kalk is why your pH is so high. Cut it back if you want to lower the pH.

bcarl77 · Jan 21, 2019

Will dosing small amounts of white vinegar effect any other elements?

jda · Jan 21, 2019

Dosing vinegar will add organic carbon to the tank. With an influx of carbon, you will grow bacteria, sometimes at a large rate. If you grow them too fast, then they can use up all of the oxygen and kill your inhabitants. I would not recommend using organic carbon without a deliberate and long-term plan.

Turn your skimmer back on if you want to raise the pH. It can mix the co2 in the air into your water. Kalk drives the co2 out of the water which is why the pH rises.

bcarl77 · Jan 22, 2019

pH bottomed out at 8.5ish last night. I don’t want to have it peak above 8.65 again.

I am away from the tank until Thursday and have limited control (fiancé) watching it. Should I kill the lights or unplug the ATO? She had some issues with the skimmer (crappy nano skimmer) starting. Could also have her grab an airstone. Not sure if I want to dose vinegar without watching it...

nereefpat · Jan 22, 2019

A weak organic acid (like vinegar) isn't a good way to control pH.

Aeration is good.

Baking soda is a great way to raise alk. It temporarily will lower pH until the CO2 is degassed.

I wouldn't worry about high pH unless you are seeing precipitation.

steallife904 · Jan 22, 2019

Could your PH probe be bad? I had a high ph issue recently and turned out my probe needed replacing.

Mical · Jan 22, 2019

With #s like those I'd be suspect of salinity

Coralfuture · Jan 22, 2019

When my alk has dropped below 6.0 dkh many corals started to bleach and bail out. At 6.2-6.5 your coralline algae will bleach. Just as an indicator of how that alk test is reading out cuz low alk and the crazy high ph is surprising. I feel something is off in the tests somehow.

bcarl77 · Jan 22, 2019

I had my fiancé triple check the reading again today with my pH pen which confirmed the high pH.

I am going to double check my salt level and verify it’s calibrated as well.

Turned off Kalk ATO and pH is not moving much hanging at 8.45...