Dramatic change in tap pH

[TomFromStLouis]

For some reason my tap water pH has gone from a very workable 7.2 to over 8.6. I noticed the change after seeing my fish respond unfavorably to a 50% water change. I checked pH and the tap water is off the charts! The test water turns a deep royal blue not even on my color chart.

I had let the tap run for some time (while pythoning out 20 gallons), so I do not think it was 'old pipe' water. Plus, the difference was noted yesterday and it persists today. The Missouri river just does not change that much. KH remains at 4. Any possible explanations? If this lasts a while, what will I do about my tank pH? All my fish and plants are meant for the water I started with!

[wetmanNY]

Are the St. Louis Water Division any help? Their website is http://www.stlwater.com/default.htm A phone call during business hours tomorrow might give you clear answers and a picture of what to expect in the future.

Tell us what you find out!

[aquariaddictus]

Tom - STL county and city both use chloramines. There is always a little more ammonia left over in excess of the amount used to react with the chlorine. I tested water for AB for 11 years, and fresh out of the tap, it was sometimes 10. If you let it sit, it comes down prety quickly. I've found that as long as I do water changes of 40% or less, my tank buffers the incoming water. In the summer however (when they up the disinfection), it can be harder to do, and I've had to use pH down before.

With the recent rains, they may have upped their use of chemicals, especially if we're getting into a runoff situation. I've killed many a fish here with a pH shift, before I realized what was going on. The alternative to a buffer would be to let the water sit in a separate reservoir if you can. pH is the only parameter I ever check, since I discovered how wildly fluctuating we are.
hth
judy

[TomFromStLouis]

Is this a great place or what?

I put a call into the water company and they are processing a 'water quality complaint' which will net me a discussion with someone knowledgable within 3 days. The person who answered the phone did not even know what pH was...

Judy,

An awesome direct hit of an answer! In short, I will always need to monitor pH from the tap, right? And in trying to deal with my current green water issues, I probably should rely on frequent smaller changes so as to not shock the little piggies, I mean angels.

I DID notice that the tank pH settled down after a few hours. I may need the tap water pH to get back to reasonable level soon for a large water change and blackout.

Thanks for the informed responses.

[aquariaddictus]

I always check my incoming, and the tank periodically as the water goes in. (I fill with a hose, and add dechlor as I go). If I have to buffer, I do, but if I fill slowly enough, it usually takes care of itself. I also found that if I had an EXTREMELY dirty tank, and did TOO big a water change, the hit would be much worse, because I had knocked out my buffering capacity. ALL those years as a water chemist, and it took me so long to apply it to fish-keeping.

I take it you're on county if you're in Clayton? Do you know for sure you're coming off the Missouri? The city uses the Mississippi and MO, and combines them, depending on conditions. The county goes with the big muddy - out at Howard Bend - or the Meremac, in Sunset Hills, where all we have to worry about is chlordane ;)

Funny, the first boss I ever had, as a yet-to-graduate Chemist, now works for county water. If the name Elizabeth Ingles comes up, that's her. I know she's pretty high up in the lab.
judy

oh, and yes, this IS a great place:D
tanks!

[nboylie]

hehe too bad you dont have african cichlid tanks and then you would be happy!

[aquariaddictus]

Good point - if you want to pick your fish according to water chemistry, cichlids are for STL. I've never been able to keep guppies, or tetras, or a lot of other fish. And I stopped trying. I AM NOT buying a water softener or RO unit. And, I love my cichlids!
j

[wetmanNY]

Tom, it sounds like they are adding quicklime to the water, to cut down on corrosion of the mains, and perhaps to "shock" some destructive thiobacilli. The quicklime is depleted in CO2, and your water arrives with that high pH as a result of CO2 depletion. Leave it in a bucket overnight with an aerator running in it, and see how that does for stabilizing pH.

[aquariaddictus]

Pretty sure we don't use quicklime here - there's enough scale built up in our distribution system as is. Our water's pretty high in calcium and alkalinity. We'll see what the ole water Co had to say.

[TomFromStLouis]

Holy Alkaline Batman! Steve from Midamerican Water said they always send out water with a pH of 9.5 -10!

Now if I had known that when I began, maybe I would have a tank of cichlids instead of angels and tetras. <sigh> He was unable to explain how I measured 7.2 when I first filled the tank, or how I get a KH of 40 when he sends out 120. The high pH comes from adding Calcium Oxide to lower the hardness from 300 he says. I really doubt the building is treating the water in some way, but that is one of the few explanations he could suggest.

So it looks like I will have to season my water a bit (not easy in an office situation) or find some kind of pH Down chemical that will not screw everything else up (muriatic acid?). I still get a KH of 4 or 40 (wherever that decimal goes) and a current pH of 6.6 (thanks to the CO2), so my tank is right where I want it for now. But water changes will have to be smaller and more frequent to avoid stress. Any other ideas water gurus?

[wetmanNY]

cut n' pasted from www.skepticalaquarist.com:

"The quicklime (calcium oxide— CaO) used in this "lime-soda" technique is produced in a kiln, where heat drives the CO2 out of crushed coral, limestone or oystershell. The resulting caustic quicklime can be finely ground and slaked with water to form hydrated lime or calcium hydroxide (Ca(OH)2), a fine powdery alkali that is strong enough to neutralize powerful acids. The slaked lime is also an efficient absorber of carbon dioxide, so tapwater treated by "lime-soda" softening generally arrives at the household tap still depleted in CO2, which contributes to its high pH. Often fishkeepers with this artificially softened water that is combined with high pH find that the pH drops somewhat after 24 hours of curing, aerating it in a water butt. For the sake of pH stability in the aquarium, lime-soda softened water should always be separately cured before using it.

In areas with soft, naturally acidic water, utilities sometimes boost the pH, to reduce corrosion in the mains, by adding calcium hydroxide alone. This can give tapwater with unusually high pH. On the whole, if tapwater has a pH >8.3 or so, you should expect that the water has been "limed."'

[TomFromStLouis]

You know WetmanNY, I found that very quotation on your site when reading about live foods and more just today. Good site. Hmmm, maybe I should spend some more time there....

Yes, you were correct about what our water company is doing to the water. Since you or someone elsewhere said something about Potassium Chloride lowering pH, (I have been reading a lot of archives and sites today) and KCl (NuSalt) being one of my ferts, maybe I could just fill a bucket, add some KCl and stir, and presto! have suitable angelfish water!

Right?

If my tank pH is 6.8 +/-, and I change 30% of the water, the highest pH of my new water should be ? to keep tank pH under 7.0? My guess is somewhere around 7.2, but if anyone can do this log math, I would appreciate it.

[ChilDawg]

7.96 is probably the upper limit.

[ChilDawg]

Crud, I did that wrong. 7.44

[TomFromStLouis]

Could you briefly run through some of the logic for me? I thought that since it was a logarithmic scale it would be more than just averaging as in 70% x 6.8 + 30% x X = 7.0 If I plug in your 7.96, I would get 7.15 (more of a change than I want), so I presume that my method is indeed faulty. So how you came up with 7.96 is a bit of a mystery to me.

Not stupid, just ignorant.

[ChilDawg]

.7 * 10 ^ -6.8 + .3 * 10 ^ -pH = 10 ^ -7.0

I kinda did it bass-ackwards, but wound up with the second number. I'll have my roomie confirm, and then send you a complete formula.

[ChilDawg]

Upon further review, there is no way to do this problem without taking equilibrium constants and hardness taken into account. It would be a hell of a lot harder than that which anyone in my dorm could do in a "reasonable" (read: less than an all-nighter) amount of time without software doing most of it for us. We don't have the software, so empirical experimentation on your part might have to suffice.

Both times, I went for too simplistic of a model, so do not take those numbers as Gospel, or even a failed attempt at Scripture.

[ChilDawg]

Under the assumption that you have water mixed with NaOH in your tap and water mixed with HCl in your tank (and no buffering), 7.41 is the max. However, your buffers will help increase this value...by how much? We may not know without empirical experimentation.

[aquariaddictus]

Hi! I owe a couple of apologies here - one to WetMan, for doubting him (the man who accepted my iodide calculations without question - shame on me, bring out the wet noodles, or string algae, whatever) All that time, and I didn't know what county water was doing. I was working with city water, and it's probably the same, just noone ever explained it. In my defense, my super also believed the residual ammonia caused the transient high pH. So sorry, WetMan, I'll read your book more closely before I open my mouth and put both feet in (yes, they fit)

Matthew - post any more of those calculations, amd I'll have you banned - I flunked that part of quant :)

Tom - how would you feel about having some pH paper that's a lot cheaper than whatever you're using to check ph?
PM me.
judy

[ChilDawg]

Apparently, I would flunk that part of quant, too, Judy, as my roommate had to explain to me what happens differently around the pH that we simply call "neutral" (head exploding, sprinting to an exit!!!)

No more pH calcs for me...don't ban me, please? I'm a good kid! :D

(I took your last statement with a grain of salt, 'cos I wouldn't want you thinking that I took it seriously this time!!!)

~Matthew

[aquariaddictus]

You're getting to understand me now - cool!