Help me solve my pH issues. Please

[Dingo]

Hello all, I am looking for some suggestions on how I can bring this pH up. See below facts:
Background and tank info- 300g display, 100g sump, refugium used to be piped in but made no difference, just took it offline and will be converting it to a frag tank. Bare bottom acro dominant system running since 2019. I am heavy nutrient in, heavy out, usually have issues with N being too low and have to feed excessively. Most of my corals grow very well, coloration is amazing. Daily spawning fish to provide even more food to corals. ORP runs at 450 average, pH is 7.7 average, Ca reactor 24/7 and kalk reactor top off. Occasionally need to add sodium bicarbonate to adjust or bring up alk when it falls below 7... otherwise alk is very stable between 7-8dkh. Skimmer line is piped outside (made no impact on pH when I did that this past January). Atmospheric CO2 levels in my house do naturally run high at a monthly average of 858 ppm but have peaked at 1100 ppm when the house is closed up tight. Opening windows has minimal impact on the pH, maybe 0.1 increase at max when I get the house CO2 levels down to 400ppm. Installing an air exchanger is an option but I do not think it will do much because opening windows down to 400ppm atmospheric CO2 makes minimal impact.

I am looking for suggestions on what to do here. What am I missing? I can see the corals that are tolerant of the pH growing like weeds but there are some pieces that I can tell prefer higher pH and are barely growing, if at all. I have been reefing since 2007 and never had to deal with such persistent pH issues like this before.

 

[penguinexdeus]

When was last time you calibrated or cleaned pH probe?

For a few months I was beating my head against a wall trying to figure out why I was always at 7.8 and wouldn't go above 8.1... right around end of fall...opened windows ect... No improvements. One day decided to test with the hanna egg pH tester and got 8.4. didn't believe the hanna...

But decided I should try a calibration anyway... Cleaned some sponges off probe that were growing and Calibrated ... Hanna was right... Now I'm 8.1 to 8.4 through the day... And not chasing pH...

 

[Dingo]

I have a second stand alone pH probe that reads slightly lower than the Apex one. I’ll calibrate for argument sake here but I’d be surprised if I have two probes both reading similarly low here.

 

[escaraba]

Do you have a closed lid on your aquarium?
More flow on the surface wil help.
Your picture looks like no flow on the surface

 

[helmsreef]

You could take down your calcium reactor and start 2 part dosing with soda ash, or use your kalk as your primary means of supplementation. Your reactor is most likely the biggest reason to your low ph

 

[helmsreef]

Also to add why is your ph so high in your reactor? What media are you using? What is your dkh of your effluent? You could have a poorly tuned reactor which could be dumping more c02 in your tank

 

[Dingo]

You could take down your calcium reactor and start 2 part dosing with soda ash, or use your kalk as your primary means of supplementation. Your reactor is most likely the biggest reason to your low ph

Also to add why is your ph so high in your reactor? What media are you using? What is your dkh of your effluent? You could have a poorly tuned reactor which could be dumping more c02 in your tank

Personal preference is Ca reactor, less maintenance.
And there are two ways to operate a Ca reactor. Most common is low effluent flow, really high dkh, low pH.
Second is higher effluent flow, lower dkh, pH higher.
One method uses effluent flow as your equilibrium point and the other uses pH as your equilibrium point.
I am open to discussion regarding this as it could be putting excessive CO2. Would look for advice from someone who has operated both ways. Also worth adding is that I took the reactor offline for a week to see if pH improved. Saw no difference.
Lastly, I am out of town and will be unable to get you an effluent dkh until Sunday. Don’t trust the sitter to handle that.

 

[helmsreef]

I’ve personally tried both ways and even though running higher ph and possibly a higher effluent drip may seem like it would in turn reduce the chance of lowering the ph it may be doing quite the opposite with lower co2 retention time and not allowing enough time convert into bicarbonate. It will progressively get better as you lower ph but at some point it will oversaturate. Thus tuning the reactor to dissolve and using the Injected co2. So knowing the effulent dkh is important to know if it’s just passing injected co2 through the reactor and back into your tank

 

[Dingo]

I will have that result on Sunday then.

 

[Randy Holmes-Farley]

This has more, including a diagnostic test to try to sort out low ph issues:

pH and the Reef Aquarium - REEFEDITION

by Randy Holmes-Farley For many aquarists, pH is not something that they have much experience with aside from their aquarium. For many, pH is almost a black box measurement: something to be considered, but whose physical meaning makes little sense to them. This article will Read more here...

www.reefedition.com

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.

 

[Dingo]

I’ve personally tried both ways and even though running higher ph and possibly a higher effluent drip may seem like it would in turn reduce the chance of lowering the ph it may be doing quite the opposite with lower co2 retention time and not allowing enough time convert into bicarbonate. It will progressively get better as you lower ph but at some point it will oversaturate. Thus tuning the reactor to dissolve and using the Injected co2. So knowing the effulent dkh is important to know if it’s just passing injected co2 through the reactor and back into your tank

The trident reads 6.4 and test came to 6.49 for tank water.
After halving the concentration of the reactor effluent I am at 13.2 so we can assume it is coming out at 26.4.
Randy, I did not conduct the aeration test yet but will be doing so tomorrow and will report back the change.

Let’s assume it is due to the high levels of co2 in my house. Removing the reactor would obviously be one option. Skimmer is already pulling outside air. Adding a refugium is not an option because I recently took my refugium of 2 years offline. There was no benefit to pH anyways and I still grow macro in my sump on opposite cycle.
Do you think increasing overall flow in the tank and system as a whole would make a difference?

 

[Dingo]

@Randy Holmes-Farley the aeration test provided a 0.04 increase in pH at a 1 hour interval with a temperature differential of 8° F between inside and outside.

 

[Randy Holmes-Farley]

@Randy Holmes-Farley the aeration test provided a 0.04 increase in pH at a 1 hour interval with a temperature differential of 8° F between inside and outside.

From what to what?

 

[jda]

I have CaRx and they are well tuned. They might not even move my pH .1 units.

If you were at 400 ppm of co2 for days and days and your pH is sill that low, then it is likely a measurement error. If you dropped that indoor co2 down to 400 for an hour and then it mixed with the rest of the home air to be 1200 again later in the day, then that won't do much.

There is a paper in my signature that teaches how to tune a CaRx to have very little impact on the tank. No pH probe - just tune it by hand. It works great once, but it takes a bit of time to get the hang of it - kinda like tuning a carburetor in the olden days where it seems terrible at first and then after a bit your car is getting better gas mileage and more power.

 

[Dingo]

For closure, this issue has been rectified. Long story short: do not buy the cheap pH calibration fluid off Amazon. After calibrating with a higher quality fluid there is and has been absolutely no issue.

 

[Randy Holmes-Farley]

Glad all is well.