New to TFP; former Leslie's customer with pretty high CH

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M

moneypit81

0
Apr 20, 2018
4
Torrance, CA
Hey folks,

Bought a house with a pool built in 1977 a few years ago but didn't really take as much care of it as I probably should have - I'd get the odd algae bloom here or there if I didn't add the chlorine granules (70% hypochlorite) but I'd shock it and everything would be alright. Relied on Leslie's for chlorine/MA/some water testing at first, but didn't really like the people there so didn't ask for much help.

Then I started noticing black algae growing in the pool and came across this forum looking for advice and saw the recommendations for pool maintenance. So I ordered the K-2600 test kit and here were my results:

FC - 1.0
CC - 0.0
pH - 7.8
TA - 100
CH - 750
CYA - < 30 ended up using all 14mL's of the vial and could still see the dot so seems like I'm low

I have a couple of questions/concerns:
#1 The CH is really high, yet the pool is still clear...I have no problem seeing 10' down to the bottom of the deep end and seeing the drain? When I pull my Hayward out there's a bunch of white chalky stuff that's accumulated on it, but other than that what's the risk of having the CH this high? PoolMath says I need to drain about 50% of my pool to fix it.

#2 Seems like I've got to start adding a ton more bleach to get my FC up - I added about 1.5 gallons of 10% liquid chlorine on Saturday thinking it would get me to 5 but obviously that didn't happen...could this be because I don't have enough CYA and the sun is just destroying the chlorine? The pool gets sun for most of the day. Or is there something in the pool that the chlorine is getting used up on?

#3 When's the best time to run the pump and add the chemicals? Morning? Evening?
 
Although your CH is quite high (750), you can still manage your pool just fine by reducing both your pH and TA some. With your current numbers, your CSI is .6 with an assumed water temperature of 72. That is high and will cause scaling over time. That's probably what you have on your Hayward (white chalky stuff). If you were to say drop your pH down to 7.4 and your TA down to 80 with muriatic acid, your CSI would drop all the way down to .1 which is in the safe range (-.3 < x < .3).

Are you sure about your CYA #? If you've been chlorinating with chlorine granules like you say, those would surely raise your CYA quite a bit every time. Could the granules be calcium hypoclorite? That would explain your high CH level. Whatever they are, you should discontinue using them, and stick to liquid chlorine. It won't add anything other than chlorine into your pool, which is what you want.

If you have black algae, you need to perform a SLAM. You should lower pH down to 7.2 and raise FC to 12 PPM, and maintain that level by testing every few hours and adding however much FC you need to get back to 12. To get started, you'll need almost 5 full gallons of 10% liquid chlorine to go from 0 - 12 FC.

Once you finish the SLAM and the pool is clean, I would definitely raise your CYA to 50. That will slow down the FC burn off from the sun. Be careful not to overshoot. Use powdered stabilizer tied off in a sock and hanging over the edge of the pool in front of a return. You can squeeze the sock every so often to get it to dissolve quicker. Once it's all dissolved, test the CYA the following day and go from there.

It doesn't really matter when you run the pump or add the chemicals. Just be consistent with it. You'll get a good feel for how much your pool uses after a while. And remember, liquid chlorine ONLY! No solids.
 
1. CH is likely high because you are using Cal Hypo to chlorinate. stop doing that. Also, report the CH of your fill water

2. FC loss is likely your lack of CYA. Calculate and dose enough to get it to 30 ppm and see if your FC loss is dramatically lessened.

3. There is no one "best" time to run pump. Solve your CH and FC issues and when pool chemistry is back where it should be, you can begin to adjust pump run time as needed.

4. Black algae is often misdiagnosed.....got a pic?
 
I double checked the CYA and it's the same.

I looked at the granules I was using and it doesn't say anything about stabilizers, but it is Cal Hypo so that explains where the calcium is coming from.

I checked my lil water and it has a CH of 230, which seems high considering PoolMath goal is in the 300-350 range. So between the Cal Hypo and my fill water as well as evaporation would explain why the Calcium is so high?

My thinking is that I may be dealing with high calcium and rather than drain the pool I should just be managing the scaling by monitoring the pH?

I haven't had a chance to take a picture of the black algae, but what else could it be if not that?

Appreciate all the advice!
 
You are correct, you can manage it without necessarily draining your pool. Just monitor the other parameters of CSI (pH, TA, water temp) PH has by far the greatest effect on CSI, so you should be able to adjust that fairly easily. Just make sure you discontinue using that cal hypo. Solid forms of chlorine are bad news as a long term chlorinating solution because they're always adding other stuff that you probably don't want like CYA or calcium and it continually builds up.
 
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