Unknown problem, possibly PH

[chewy tabacca]

To start,
Alk 9.5
Cal 410
Mag 1380
Po4 0.03
No3 7ppm

Now that that's out of the way my tank has been up for around 3 years I have had my ups and downs that's for sure, recently I have been going through a down. The past month my corals have been receding, no moralities yet but in a month or so there will be. Once the tank started down I went and bought an apex. My PH at night is reading 7.71. I have calibrated the probe 5 times in the past month and the salifert test is reading 8.3. I am running a aqueon air pump into my skimmer from outside, my wife and I are the only ones in the house, and I have 2 recirculating Co2 scrubbers. It's over kill and I still can't get the PH up.

 

[lapin]

A PH of 7.7 is not really low.
Since your tank has been running for 3 years and your numbers look in line. My first thought is that something might have changed in your source water. Possibilities are heavy metals, chemicals or excess DOC's.

 

[chewy tabacca]

A PH of 7.7 is not really low.
Since your tank has been running for 3 years and your numbers look in line. My first thought is that something might have changed in your source water. Possibilities are heavy metals, chemicals or excess DOC's.

Ya, I just upgraded my 5 stage to a 7 about 6 months or so ago as well to make sure it is the best it can be

 

[W1ngz]

Not sure about the pH thing. Even if it really is 7.7, that would slow growth but shouldn't kill anything. I have a few ideas to help eliminate that from your list.

How deep in the water is your probe? With mine, I get a lower ph reading the deeper it is in the water. I mounted it high so that not much more than the tip is submerged, which is how the probe was calibrated.

Do you have a direct comparison of test kit and apex values at your peak and low ph period? Do they show more or less the same variance?

 

[BeejReef]

Any chance the tank has just grown out and things are getting more shaded or less flow than they used to?
Have you always run very low N and P?

 

[chewy tabacca]

Not sure about the pH thing. Even if it really is 7.7, that would slow growth but shouldn't kill anything. I have a few ideas to help eliminate that from your list.

How deep in the water is your probe? With mine, I get a lower ph reading the deeper it is in the water. I mounted it high so that not much more than the tip is submerged, which is how the probe was calibrated.

Do you have a direct comparison of test kit and apex values at your peak and low ph period? Do they show more or less the same variance?

That is a smart way of thinking, my probes are buried with only about half an inch out of the water. The only test kit I have for PH is salifert

 

[chewy tabacca]

Any chance the tank has just grown out and things are getting more shaded or less flow than they used to?
Have you always run very low N and P?

Not entirely have I run low nutrients, I am trying to bump it back up but my tank is a machine at ridding itself lol. Ironically the frags are the ones suffering, my colonies all look mint

 

[BeejReef]

Not entirely have I run low nutrients, I am trying to bump it back up but my tank is a machine at ridding itself lol. Ironically the frags are the ones suffering, my colonies all look mint

Oh.. good! I read your post as you thought you were about to start losing colonies or even the tank.

Are the struggling frags new to the system, or are they frags of some of your mother colonies?

 

[jaxredsoxfan]

Where in the system does your probe for the apex reside. If possible put it in your main display and see if the numbers are the same. Maybe its getting cleaned/skimmed water to the probe in the sump?

 

[chewy tabacca]

Oh.. good! I read your post as you thought you were about to start losing colonies or even the tank.

Are the struggling frags new to the system, or are they frags of some of your mother colonies?

They are 'new to the tank' some are a month plus old, encrusted the plug but now dying slowly from the tips down

 

[chewy tabacca]

Where in the system does your probe for the apex reside. If possible put it in your main display and see if the numbers are the same. Maybe its getting cleaned/skimmed water to the probe in the sump?

In the sump aft the skimmer, right after the scrubbers where the return pump is

 

[jaxredsoxfan]

i would try and set it in the display and see if it reads the same. Generally I try and place probes before any filtration or skimmers.