First steps since refilling + waterfall question

[laughingboy]

With all your good advice, I'm on my way to bringing my pool up to speed. Here's what I've done so far.

Last night before I added anything the numbers were as follows:

FC 0 CH 225 pH 8.0+

I added a bag of trichlor shock and about 2 lbs 8 oz of CYA to approach 20+ CYA en route to a goal of 30.

This morning I remeasured:

FC 3.5 CC 0.5 pH 7.6

I did nothing and remeasured this evening:

FC 0.5 pH: ~7.9 CH 200 TA 145

I'm shooting for the following goals:

FC 4 pH 7.2 CH 300? CYA 30 TA 80

Note my pH goal of 7.2 is to help lower the TA; once TA is reasonable I want a pH closer to 7.5.

Based off of these goals and the results of the pool calculator, tonight I added ~72 oz of 6% bleach and ~32 oz of muriatic acid. I've also turned on the waterfall to help aerate the water.

I assume the pool calculator doesn't really take into account the high pH of the bleach, so I have probably underestimated the amount of acid necessary.

Does all this sound reasonable?

Also, based on my other reading, aerating the water will help raise the pH, which is useful for me right now since it will allow me to repeatedly use the muriatic acid of a means of ratcheting down the TA without cumulatively lowering my pH.

Once I've done this, however, what's your advice on running my waterfall? I hadn't thought about its effects until now. My automatic cycle for the pool runs the pump with the waterfall about 7 hours every day. Of course I sometimes also turn on the waterfall because it looks cool :-) Does all of this running the waterfall create an additional acid demand on the pool?

Thanks,
Mike

[CarlD]

You've done very well for a 1st post! Very few grasp as much as you have as a newbie.

OK, a few things:
1) I fear you are going to over-shoot your CYA mark. It's never advisable to add everything at once to hit a target, particularly with CYA. It can take 48 hours to a week for it all to dissolve in and give you a true reading.

Tri-Chlor tablets add CYA as well--I think for every 10ppm of chlorine it adds 6ppm of CYA. Plus they are extremely acidic. Keep checking you CYA levels, don't add any more and let us know where it lands. There ARE advantages to higher CYA levels especially in a hot, wet, humid summer, but adjustments must be made. aylad, our Louisiana moderator, finds she must run higher CYA levels than Poconos or I do, in the NE, in order to maintain her chlorine levels.

2) What size pool do you have? Is it vinyl, fiberglass, or hard-sided (concrete, plaster, tile)? Unless it's hard-sided, or you have an SWG, you are worrying over your T/A of 145 needlessly. But with a waterfall I'm guessing it's hard-sided.

But if you are going to lower T/A, you don't want to aerate at the same time you are lowering pH--Aeration, as you correctly read, raises pH. Use the Muriatic Acid to lower pH and bring T/A down with it, then use aeration to raise it. So turn off the waterfall when you are lowering pH, and turn it back on to raise it.

3) I tend to keep it simple. I avoid "acid demand" and our chemistry experts tell us the acid demand test is wildly variable, so I just watch pH and if it's too high, add acid in small increments. Since I have a 20,000 gallon pool, I'll add 1 cup of acid at a time, diluted in a five gallon bucket of water first, then wait and test. With acid, borax, CYA, calcium, etc, you ALWAYS want to add LESS than you calculate--usually 1/3 to 1/2, not more. You can always add more. Add, wait and test, add wait and test.

Caveat: With chlorine, this rule does not apply. If you hesitate, you risk algae. Plus, if as I guessed you have a concrete/gunite/plaster (whatever) pool, it can tolerate unbelievably high levels--where vinyl will begin to bleach out. Yet with both, overshooting your target FC is better than undershooting it.

Despite the tables and the tests, we have found that every pool is different and owners must learn what works in their own pool. Chem_Geek and PoolDoctor can probably explain why when there are two similar pools with the same numbers, one will have a constantly rising pH, and the other a heavy chlorine demand. The moral? Test and track your pool on the basic tests: Chlorine, pH, T/A, CH and CYA and let those numbers dictate what you do. It's almost as if everyone's water has a personality! Hard to believe but after nearly 10 years here, it happens too often not to believe.

4) Testing: I notice sometimes you post FC and CC, sometimes just FC. Does that mean CC is 0 (the target) or you just didn't measure it? You should always measure CC if you are measuring FC. It's always best to post the full suite of tests and in a column so it's easy to follow:
FC: xx
CC: xx (or TC, since TC = FC + CC)
pH: xx
T/A: xx
CYA: xx
CH: xx
You don't need to post the acid or base demand tests.

I think you are in pretty good shape. Just be conservative, use bleach, and keep on top of your numbers and you'll be fine.

Welcome!

[laughingboy]

You give me a bit too much credit Carl -- I've posted on here a couple of times before. I also foolishly assumed readers would know my pool specs from those prior posts; I've now corrected that with the info in my signature.

I'm surprised by your comment about the importance of measuring CC. I naively assumed that since CC doesn't affect balance and it doesn't help sanitize the pool, it isn't all that critical to measure. What am I missing?

The point about the waterfall and aerating may be moot. I've discovered to my disappointment that I basically can't run my pool pump on high for very long if I don't also run the waterfall -- for some reason it switches to a low speed mode which seems pretty useless to me. I can just barely feel the water pulsing slowly through my Kreepy Krawly which itself doesn't run with the low pressure. So when I'm adding chemicals, my choices seem to be to run at low (useless?) speed or run with the waterfall turned on. FWIW, I asked the pool contractor who drained the pool for me about this and he said as a practical matter the waterfall shouldn't have much of an aerating effect.

My biggest problem right now is that ISTM that I'm adding an awful lot of acid and bleach without making much headway, especially in the pH / TA department. Here's the most recent history of measurements and additions (missing measurement means it wasn't measured):

Goals:

FC 4
pH 7.2 (interim goal for ratcheting down TA, ultimate goal is 7.5)
TA 80
CH 300?
CYA 30

6/25 evening:

FC 1
pH 7.9
TA 100
CH 225
CYA < 30 (still see the dot somewhat with tube completely full)

added 44 oz of 14.5% muriatic acid, no bleach (got called away)

note: acid levels added are approx 50% of pool calculator recommendation

6/26 morning:

FC 0.5
CC 0
pH 7.5
TA 100

added 26 oz of 14.5% muriatic acid, 108 oz 6% bleach

6/26 evening:

FC 2
CC 0
pH 7.6
TA 125

after dark I will add 40 oz acid, 62 oz bleach

Bather load is 0. My TA is actually rising! (To be fair, I'm using 25 ppm / drop titrations, so perhaps it is basically staying the same within the margin of error).

Should I be more aggressive with my acid additions? Should I consider adding more CYA? I hope I won't be forced to live with this level of acid / bleach consumption on an ongoing basis.

Also, I should note that I'm still trying to get the hang of properly reading the pH colors. I've now started bouncing the sunlight off my white notebook paper -- does that seem reasonable?

[Watermom]

I wouldn't add any more cya yet. You just added it yesterday if I am reading your post above correctly. It will take about a week for it to dissolve so if you add more now, you may overshoot your target. Wait awhile until you retest cya so you don't waste your reagents.

Go ahead and add a bit more acid at a time to get the pH down to 7.2. Closely monitor the pH and if you accidentally take it too low, just add some Borax.

The reason we want to see a CC reading is to help us see if something is brewing in the water. Often, before you can see anything green or cloudy, you'll have a CC reading and that is a red flag to alert you to step up the chlorine. That is why Carl asked for it.

Sounds like you are doing well learning how to handle the pool. Good job and keep us posted how things are going.

Oh --- one more thing --- the white paper behind the tester is a good idea. Hope this helps!

[laughingboy]

I think I screwed up the timeframe for adding the CYA on my other post -- I actually added it the night of the 23rd, so it's been about three full days, but in any event I take your point. The CYA test is especially expensive in terms of reagents -- it uses 7 ml each time along with 7 ml of water. I've maybe tested 3 times and I'm already about halfway through my supply.

I suppose you could mix up less as long as it was 50/50 if your CYA level was high. That doesn't do me any good right now. They really need to make a more sensitive reagent :-)

[CarlD]

The CYA test is intensive. I actually have a pint bottle of the reagent in a closet to refill the little bottles in the kits.

Unless your waterfall is a dribble, it will aerate your pool. Hate to say it, but the builder is probably wrong. Even pointing your returns at the surface aerates. On one of the few times I needed to lower TA, I used a cheap fountain sprayer the screws into the return. It was a lot of fun for the kids and worked very rapidly to raise pH.

As Watermom said, CC is a bell-weather. If you have a measurable level of Combined Chloramines, it means your chlorine is working to metabolize something, so you may have to shock your pool to get rid of that "something".