Thanks To All!! Clear Pool At Last

[chem geek]

Yes, gunite is technically sprayed concrete, but the calcium carbonate that we are concerned with is part of Portland cement that is part of concrete, mortar and most grout. So I've been loosely saying plaster/grout when I should really be saying shotcrete/gunite/concrete/mortar/grout/plaster (what a mouthful!). Technically, a pure plaster (not concrete plaster) is calcium sulfate (usually derived from gypsum) which also needs calcium for equilibrium, but sulfate as well (at any rate, this kind of pure plaster isn't in pools -- only concrete plaster is). But I digress...

My understanding of typical in-ground pool construction (and my understanding is quite limited) is that they dig a hole in the ground, place rebar, spray with gunite (actually spray concrete in a mixing technique that has this named gunite) and then finish with a concrete plaster surface with some tile at the top that has grout in between. So technically, the sprayed concrete (gunite) and the concrete plaster on top of it as well as the grout between the tiles contain calcium carbonate. So yes, your pool needs calcium (and carbonate, which is most of your TA) in the water.

As for your calcium test, I don't have the Taylor guide booklet with me, but I do recall it saying something about certain substances interfering with the calcium test, but I don't recall what it is. Perhaps someone else out there on this forum knows what can "bleach out" the calcium test. At any rate, it does appear that you have calcium in your pool and yes, in my experience the deep red drops usually sink to the bottom so you have to mix (shake) to get the pinkish color. If you are doing the test I believe you are, then the 40 drops means 400 ppm calcium hardness which would normally be OK except that you also have high TA (160) and high pH (7.8). That combination in theory gets you close to scaling (precipitating) calcium carbonate though I've learned that this often doesn't happen and you would likely see your water get cloudy first.

At any rate, we've already talked about you doing a partial drain and refill to try to lower both your CYA and your TA and this will also lower your CH as well, so that's really the easiest way to get down to better numbers. After that is done, then you can repost your results and we can see what else needs to be done, if anything. It may be that you will need to get your TA down even more (to 80-100), but work on one thing at a time (i.e. partial drain and refill first) or else you'll go nuts trying to simultaneously get it all right!

[EDIT] WHOOPS! Reread your post about the water ban. OK, here's what you can do instead. Follow Ben's procedure for lowering TA by first lowering pH (by adding acid) and then aerating. By significantly lowering your TA to 100, you should be able to have your pH remain somewhat stable at 7.5 and this combination will be better for you given your CH of 400 (it should also have pH rise less and have you adding less acid). With your high CYA, you will need to keep your chlorine up according to Ben's Best Guess CYA chart, but you'll have to live with that (and adding chlorine regularly) until you are able to partially drain and refill your pool again.[END-EDIT]

Richard

[karenkr]

Thanks
I have some PH Minus left over from the beginning of the summer. Would it be ok to use it. States on side of bottle use 16 oz--thought I would start with 8oz and go from there. or should I buy some acid?
I have been maintaining my cl level about 8 (per chart) and right now my pool is crystal clear. The grandkids do say that it stings the eyes a little if they are in for quite awhile. I am assuming that this is because of the high chlorine level--correct?
Sure appreciate your help and PATIENCE that you have shown me
Karen

[chem geek]

No problem -- we're all here to help each other.

Can you see what it says the active ingredient is in the pH Minus? It might be Sodium Bisulfate which will add sulfate to your pool. Though that's not the best thing in the world, the amount is rather small since you won't use this all the time so I think it's OK to use this stuff and then in the future use Muriatic Acid (which is a liquid). However, Ben's technique for lowering TA usually takes quite a lot of acid, both for the initial lowering and for the continual adding and testing during aeration, so you might be better off getting the Muriatic Acid anyway.

I doubt that the high chlolrine level is causing the stinging of the eyes since you've got so much CYA to "hide" the disinfecting chlorine. Usually it isn't free chlorine that stings anyway -- it's usually a pH that is too low (maybe also if it's too high though I haven't heard that before) or its combined chlorine (CC). Your pH is a bit on the high side so that might be it, but it is possible of course that the chlorine levels are causing this (from the "bound" chlorine to CYA) and I'm just wrong.

Richard

[waterbear]

If your plaster is bad I would stay away from the dry acid....both sulfates and high cya levels have been implicated in pitting of plaster finishes in pools.
What hardness test are you using? It seems like you are either using the Taylor test or Ben's....there are 3 reagents in this test. If you are using a test that only uses 2 reagents then most likely it is testing total hardness and not calcium hardness.
Also, what brand of cal hypo is your ace hardware selling? Our store has the HTH on sale and it is only 48%

[karenkr]

If I dont use acid what should I use(if anything) to lower my ph and TA? My test kit is the one from Walmarts. I read on there that the total hardness test is the measurement of calcium and magnesium carbonate in the pool. Am I testing for the wrong thing????
The brand of cal hypo is HTH and the bag says Super Shock with chlorine at 60%. Its on sale for 2.50 a bag, the gallon of bleach at 10% is on sale for 2.59 for a gallon. Is it still alright if I use the super shock?
Waterbear: you said the acid might harm my pool---what about the PH Minus? Ingredients state Sodium Bisulfate 92% and inert ingredients 8%.
Sorry I am so dumb about these things, it seems like I think I get things straight in my mind then something else pops up and CONFUSION sets in---maybe its an age thing(HA HA)
Anyway thanks for your help and PLEASE dont give up on me.
Karen

[chem geek]

You can use Muriatic Acid which is a liquid that you can pour slowly into your pool near a water return outlet so that will mix the acid quickly with your pool water to prevent damage to the plaster. I didn't know about the problems Evan (waterbear) mentioned about using dry acid, but it makes sense and fortunately Muriatic Acid is the best alternative. There isn't any other way to lower pH other than adding acid.

As for the test kit question, I'll leave that to waterbear since I am not familiar with the Walmart kit(s). If the test kit says it measures Total Hardness (which is Magnesium and Calcium) then that is not what is important to measure -- it is Calcium Hardness that you want to measure. Typically, Calcium is the larger component of hardness so if your total hardness was 400 then your calcium hardness might be 300, but you really need to do the right test to know for certain.

The Sodium Bisulfate is dry acid that waterbear is talking about so based on what he said, don't use that and instead get the Muriatic Acid which is a liquid that typically comes in a quart plastic bottle. [EDIT] I meant "gallon jugs" just like waterbear said below. It's getting late... [END-EDIT]

Are you kidding? We will never give up on you.

Richard

[waterbear]

yep, it tests total hardness...and there are some known issues with the test that have been discussed on the forum before so it is not the most accurate. It is not what you need. You need a calcium hardness test such as the one in Ben's test kit or a taylor K-2006

As far as acid goes, use muriatic...comes in gallon jugs. Be aware that this is just another name for hydrochloric acid so have some repect for it.