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View Full Version : PH Issues - Again (shoot me)


zoomen
03/19/2012, 11:45 AM
Hi - My continuing issues with testing have really started to sour me on this hobby. I was at a point last night - I was about to launch my PH probes into my dog's toy box.

I have a new unit with new probes to replace my busted apex which is on its way in for repair. I did a water change yesterday (pre change PH was 8.2) and after my water change the value is now 7.90. Is this possible? I have around 400 total system gallons and I changed 100 gallons. The salt mix is from a brand new bag of Red Sea Salt Mix.

I took of cup of the new saltwater (from the freshly made batch) and put the PH probe in it and oddly enough the PH dropped in that mix to 7.57. To rule out PH probe issues, I opened up a 7.0 and 10.0 calibration solution and tested the probe in each solution - the probes were accurate to +/- .05 points.

Since it was late - I didn't have much time to test except for KH. For my tank - with my Red Sea Pro test kit KH= 10dkh with my Elos KH= 9dkh. Measurments of the fresh batch - Red Sea = 9.0 Elos 8.5

What the heck is going on? Is this detrimental to my tank? Should I add an agent to bring up my PH?

jamey1015
03/19/2012, 05:43 PM
How are all your corals?

If all looks fine I wouldn't even worry about your PH.

8.2 is fine so is 7.9

It seems like a lot of guys get caught up worrying about there ph when there is no reason to do so.

If I were you I would just take a break from worrying about it, there's so many people who have great tanks and never check it, think the "kiss" principle and there's enough other things to worry about anyways.

bertoni
03/19/2012, 08:10 PM
The pH of the water is set by the carbon dioxide content of the air and the alkalinity. For tanks with normal alkalinity (7-11 dKH), low pH levels like 7.9 are common for houses with the windows shut. That level is fine, and I would stop worry about the pH.

Fresh saltwater might take some time to aerate and reach a reasonable pH. I thought most salt mixes started at a high pH, but I wouldn't worry about the salt product if the alkalinity is okay.

bertoni
03/19/2012, 08:11 PM
The pH of the water is set by the carbon dioxide content of the air and the alkalinity. For tanks with normal alkalinity (7-11 dKH), low pH levels like 7.9 are common for houses with the windows shut. That level is fine, and I would stop worry about the pH.

Fresh saltwater might take some time to aerate and reach a reasonable pH. I thought most salt mixes started at a high pH, but I wouldn't worry about the salt product if the alkalinity is okay.

zoomen
03/20/2012, 09:45 AM
Bertoni & Jamey1015 - I'm confused (and it doesn't take much) - from all the reading i've done - I thought PH was as critical to monitor as KH, CA and MG. So from your responses I shouldn't worry about PH - provided my corals and other chemistry is good?

My acans and brains and plates are all shriveled up, my frogspawn and elegance look ok but not as extended, but my leathers look great.

My KH is 9 to 10dkh, my CA is 500 and my MG is 1300.

disc1
03/20/2012, 09:52 AM
pH isn't that critical. Seawater with the proper alkalinity will have an appropriate pH. It really can't help it. You will only see pH vary from water to water over about 1pH unit. From around 7.8 or so up to about 8.5 or so. When were talking about pH so close to neutral, 1 unit is a pretty small change.

I think people tend to put too much emphasis on pH simply because it is something they've heard of before and think they understand. Alkalinity is FAR more important number to monitor.

zoomen
03/20/2012, 10:48 AM
Thanks disc1 & others - this makes me feel better.

I did try the "Outside Air" test. I bought a big air pump and 20 feet of hose, I put the pump outside and ran the airhose/airstone over to the sump and let it run over night. I also took a cup of tank water and used another pump pushing outside air as well.


The PH for the tank with outside air (after 12 hours) is 7.99. The PH for the cup of water with an airstone pushing outside air is 8.05. Maybe it'll take longer for an airstone pushing outside air to affect the PH of a system with 400gallons but I would have expected the cup of water's PH to raise much more significantly with 12 hours of aeration from outside air - if the problem was CO related.

Now that I know that PH isn't critical for my tank provided KH is where it should be - but I'm just generally confused why my PH would drop like a stone. My bigger concern now is whether or not my test kits are bad since nothing I've read tells me that I should have PH that low when my Alk is at 9 to 10dkh (especially after ruling out a CO issue). I was hoping the fact that my corals aren't the happiest would have been solved by correcting the PH - but now that I know it won't matter - i've got to figure out what other issues might be going on.

drummereef
03/20/2012, 12:29 PM
It's 72F in Boston, MA today. Open up the windows and watch your pH rise. :)

zoomen
03/20/2012, 12:34 PM
It's 72F in Boston, MA today. Open up the windows and watch your pH rise. :)

Its so nice out - I'm thinking of rolling the tank outside to the deck. :)

Left them open when I left this morning - I'm anxious to see what the readings are when I return!

bertoni
03/20/2012, 04:57 PM
If the pH rose only to 8.05, the pH meter or the alkalinity kit likely is having a problem. Both issues seem to crop up a lot, so it's hard to guess which one is the issue here. Personally, I'd get a second opinion on the alkalinity kit and ignore the pH.

zoomen
03/21/2012, 08:00 AM
bertoni - I came home after a full day of open windows yesterday and the PH was not much better 8.06.

I'll pick up some new Alk test kits to verify since I don't believe the issue is with the probes. First of all I have 2 probes (1 in the sump and 1 in the DT) and both are consistent with each other; Second these probes are brand new (less than 2 weeks old) and lastly; when I put the probes in 7.0 and 10.0 calibration solution to check values they both are spot on.

I'm perplexed with the KH test kits if they are bad because I used 2 seperate brands for validation (Elos and Red Sea Pro KH) - both were within a point of each other, but I will admit that both are probably close to a year old now.

I'm less worried about the PH, but really confused as to what's going on since everything I've read from what people say is that the PH should work relative to KH provided there's not an abundance of CO.

bertoni
03/21/2012, 03:03 PM
I guess the calibration solutions could be an issue, too. That's been a problem in the past.

Another issue could be the aeration rate of the tank. Does the tank have a skimmer?

zoomen
03/21/2012, 04:41 PM
I guess the calibration solutions could be an issue, too. That's been a problem in the past.

Another issue could be the aeration rate of the tank. Does the tank have a skimmer?


Calibration fluid? As in the batch I have may be bad? Would that happen with age? The reason I ask is because the solution packets are new (bought them when I bought the new probes). I do have a couple of packets of calibration solution from a different company - I could try those to recalibrate my probes - however those are definitely at least a year old (don't know if they have a shelf life).

As far as a skimmer goes - yes I have a vertex alpha cone 250. Also in case you ask; I have an 1800 gallon return pump with 3' of head pressure and 4 mp40's usually running at 90% reef crest mode.

rpjaws74
03/21/2012, 06:17 PM
Wow didnt know the air in the house could have an impact on the ph ...interesting..

bertoni
03/21/2012, 11:13 PM
Once opened, all calibration solutions start absorbing gasses from the air and will lose accuracy. They have a limited shelf life, as well. The one-shot pouches (which I used) eliminate the first issue. :) What brand are your solutions?

You can make a rough DIY check solution: 1/2 tsp of borax added to one quart of RO/DI water yields a solution with a pH of about 9.2. That might be an easy sanity test to try.

That flow sounds reasonable to me. Does the tank have good water surface agitation? That can help by preventing oily films on the surface.

zoomen
03/22/2012, 06:23 AM
The one-shot pouches (which I used) eliminate the first issue. :) What brand are your solutions?

That flow sounds reasonable to me. Does the tank have good water surface agitation? That can help by preventing oily films on the surface.

I use the one shot pouches as well - the pouch doesn't say the manufacturer name, but I bought them directly from Neptune when I bought my probes. There is an expiration date on them for 05/2013.

I'll check the DIY method you mention today after work.

Agitation on the surface is intense - I think I have more movement on the surface than any other tank I've seen. No oil spots - ripples across the entire surface.

Can high PO4 cause low PH if KH is high and CO is not an issue? The reason I ask is because I haven't checked the PO4 value in at least a year. To this point ive done a monthly 100 gallon water change and have no SPS and no cyno issues - so I've been slack in getting that value tested.

zoomen
03/22/2012, 08:28 AM
Here's a pic of my water surface (looking up) - it was early this morning so the MP40's were still in "Night Mode" - so it's 50% of what the usual flow is. I think even at 50% the agitation looks decent.

bertoni
03/22/2012, 10:10 PM
That looks okay to me. The phosphate level would have to be unreasonably high to have any effect on the pH, if it could do that at all. Something else must be happening. I'm not sure what, though.

zoomen
03/23/2012, 02:58 PM
That looks okay to me. The phosphate level would have to be unreasonably high to have any effect on the pH, if it could do that at all. Something else must be happening. I'm not sure what, though.

Bertoni - I finally checked my PO4 and it's registering a 0.36 (crazy high I know). My bad for overfeeding the tank to keep my tangs fat & happy. I'll spend the weekend reading up on the most effective ways to reduce that issue. My guess is that this may be why some of my corals haven't been too happy. Is a PO4 that high - high enough to drop my PH?

Another revelation - I've noticed over the last 36 hours or so that my PH has been gradually climbing up to 8.11. I haven't done anything different over the last few days that's any different than the days immediately after my water change.

Can it simply be that my batch of salt mix had some sort of imbalance in the chemistry that dropped my PH down so far and that the natural chemistry of the tank is finally counter-acting it?

The more I think about it the more I think it has to be related somehow to that water change. CO wouldn't create a drop that severe in the matter of a day when the entire winter had no effect on the PH. It's just too coincidental that my PH problems started with the water change.

bertoni
03/23/2012, 07:20 PM
That's not nearly high enough to be an issue for the pH, although corals might have a problem.

In theory, if the salt mix had a lot of organic acids, it could drop the pH (and alkalinity) temporarily, but I don't know enough chemistry to judge whether that's a possibility. I tend to suspect something else was happening. Maybe a spawning event triggered by the water change might have some effect.