New Pool Owner Calc Hardness Seems High

[rdhetrick]

Hi Everyone,

I just bought a new house with a pool, first pool I've ever owned. The previous owner used a chemical service, and apparently they came once a week. From what I can tell, they basically add CYA twice per year, and liquid chlorine every week. All that for $50 per month - what a deal, wink wink.

Some things I've noticed about the pool, the water looks pretty clear to me. No obvious signs of algae or anything. Around the waterline tile, there is some white scaling.

I've been reading a lot here for the past week or so, read through Pool School, and just got a Taylor K-2006 test kit today. Here's what I tested:
25k gal, In ground, plaster, North Texas
Water Temp: 76
FC 17.5
CC 0
pH 7.6
TA 140
CH 370
CYA 85

I was surprised at the FC so I retested it and got the same thing.

My first thought is that the CH is too high and is the cause of the scaling. From what I've learned, I should lower the pH by adding muriatic acid and I think this would then bring the CH down?

I plan to take a sample to Leslies in the morning to see if they get the same readings I got above.

Thanks in advance,
Rob

 

[supertune]

Hi rdhetrick and welcome to TFP!
If you do go to the pool store, take what they say with a grain of salt. (Don't trust pool stores)
You have a Taylor drop based system. Taylor kit reagents are the best in the industry and is the same reagents comes in the TF-100 kits from tftestkits.net, which is what most of us use here for testing.

Stay with your results, just re-read the newer testing instructions here:
extended-test-kit-directions-t25081.html

A speed-stir is also a great addition to your test kit. I love mine.
Get familiar with the pool calculator.
Plug in your numbers and check your csi for plaster pools.
See the recommended levels here in Pool School:
pool-school/recommended_levels
Some of the other more experienced members will probably chime in.

Chuck

 

[linen]

Welcome to tfp, rehetrick

I was surprised at the FC so I retested it and got the same thing.

How were you measuring FC prior to the taylor kit? What is your method of chlorination?

My first thought is that the CH is too high and is the cause of the scaling. From what I've learned, I should lower the pH by adding muriatic acid and I think this would then bring the CH down?

It will not bring CH down, that can only be done by drain/refill cycles or reverse osmosis (RO) treatments. What is the CH and TA of you fill water?

Have you plugged your numbers into the poolcalculator.com com yet? The calculator has a calculation called CSI. The guideline is if your csi is 0.6 or higher, then you are at risk for calcium scaling. I get 0.35 for your pool with your numbers, but if I put in 8.0 for ph, then I get 0.74 csi. So yes, keep your ph lower for not (down to 7.2) and not above the current 7.6 to prevent more[/url]scaling. Lowering you TA down to below 90 will also help. Play with the calculator, it will show you what is good and bad for csi.

Your cya level is also quite high at 85. We recommend 30-50 ppm for a bleach/liquid chlorine pool. You might be able to live with 85, but you will need to keep your FC minimum level higher...see:http://www.troublefreepool.com/pool-school/chlorine_cya_chart_shock Only way to lower is to drain/refill or RO.

I plan to take a sample to Leslies in the morning to see if they get the same readings I got above.

I would trust your readings and not mess with the pool store.