unexplained drop in pH

[geno]

I do a 10% water change every weekend; i.e. 10 gallons in my 125g with tons of LR.

I noticed this morning (Tuesday) that my pH had droped to a dangerous level of about 7.5 -- I know raising it fast is out of the question -- so I have two questions:

1. What is the best way to raise it carefully?

2. What could be causing the drop?

Tank background: 125g with sump and skimmer; Lots of LR; 6 fish; assorted corals (all LPS); 3 x 150 MH lights with 4 x 96 PC; Measured parms on Sunday with everything at 0 and pH at 8.2; KH = 7 (using the Elos test kit).

Thanks for any and all suggestions.

-geno

 

[xyzpdq0121]

What are you using to measure your PH? If it is a probe, check to make sure there is not an air bubble or anything on the probe.

 

[geno]

Brandon,

I am using the probe on my ACJr. I also repositioned it this weekend. Good call.

I tested the water this morning using my API test kit (5 drops / 5ml) -- it read about 7.5 as well.

I'm starting to add (as prescribed) the Brightwell product called Alkalinity 8.3

Thanks for the follow up.

-gene

 

[xyzpdq0121]

Your KH is not bad... What is your Mag and your CA? I mean it is very odd for a PH to drop that much, that quickly without a mechanical failure. You using RO water for new water and top off? Take your probe out and measure a glass of RO water and see what you get.

Other then that, I am out of ideas for testing a "bad" reading...

 

[geno]

I don't have a Mag kit -- CA was about 320

Yes indeed -- I only use RO water. I've been buying it at Kroger lately since I hate to waste so much in the process. I took a reading of the RO water from Kroger this weekend -- it was 1.

I'll test the probe as you recommended and get back to you.

-gene

 

[xyzpdq0121]

PH from the RO water from Kroger was 1?!? Or TDS was one?!? If the PH was 1 then there is your problem... (Note: I doubt it was considering it would kill you to drink it!)

 

[geno]

Brandon,

Sorry for the alarm -- I pulled the probe from the tank and found it dirty -- I shoved it into one of the overflows and when it hit bottom it became fouled.

Not sure why my first reading using the API kit was so off -- I just moved the probe to the DT and got a reading of 8.05 and rising. The kit now reads 8.4 -- what the heck!

I'm becoming convinced that the API kit may not be reliable enough for me.

-gene

 

[xyzpdq0121]

LOL... I knew it had to be an error... Don't worry, I just went through the same thing the other day. If it keeps happening, the probe could be going bad (should be replaced about once a year).

 

[geno]

I didn't see your earlier question about the water from Kroger.

It had a TDS = 1 (not the pH). I figure a TDS of 1 at 29-cents/gallon is a pretty good deal. I just load up every week with 15 gallons.

I have a white 32 gallon Brute that I plumbed with a spigot -- it's pretty convenient for now.

I love this board!