New Pool Owner, Old Pool Water

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J

JPhresh

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Dec 21, 2014
24
Clayton, CA
So my wife and I bought a house with a pool back in August, which is a first for both of us... It's a lovely thing with a Pebble Tec finish, but it's becoming clear to me that the previous owners neglected it, along with almost everything else about the house (that's another story). Anyhow, I hired a pool guy when we moved in, who assured me everything was fine... Then after a couple of months he simply stopped coming. No answers to emails, no phone calls, no bills -- just *poof*. I decided it was a sign that I should start managing the pool myself, so I bought some crappy test strips and, based on those and some pool-store-guy advice, ended up putting two small bags of chlorine powder (I think it was stabilized) in the pool in late September (yes this is northern California and we were still using the pool). I have also been religiously keeping the floating chlorine dispenser stocked with Kemtek 3" tablets (which, in retrospect, is probably a mistake) and manually scrubbing the pool once every two weeks to keep the algae from getting a foothold.

My early Christmas presents this year were a Barracuda G3 (to replace the defective Navigator) and a Taylor test kit... The latter altered me to what I had been suspecting for some time -- my chemistry is out of whack:

FC 1.6
CC <0.2
pH 8.0
TA 100
CH 500
CYA >100 (way above... I think at least 200. Need to run a dilution test.)
Temp 55F

This leads to a lot of questions, but my first and foremost question is about the CYA... My research suggests there is no option to fix that other than changing out a significant portion of the water. Is that correct? Assuming it is, if I rerun my CYA with dilution and find it's 200, what percentage of the water do I need to remove and replace?

Other, less burning questions:
I assume the high pH issue will also be resolved by replacing the water... Correct?
How did the water get so far out of balance (was it using the tablets?) and what can I do to prevent that in the future?
Once I do the water replacement, what are the next steps to getting the water properly conditioned?
Is it okay to let the pool slide until the spring (ain't no one swimming in 55F water), or do I need to address this soon?
My pool has an unusual shape, so I'm not sure about the volume since the usual online calculators aren't quite applicable... Are there other methods of figuring this out?

I'm sure I'll think of other questions, but this is a good start... Thanks in advance for your help!
-J Phresh
 
Welcome to TFP!

It would be good to measure your fill water TA and CH levels. Hopefully they are both fairly low. If either is 50 or higher you will need to adjust how you approach things a little.

Typically you replace roughly half of the water, then test CYA again and see if you need to repeat the procedure.
 
your FC seems pretty low.

I had the same algae problem when I moved into my house in september and was getting started.
every other week my fc was getting below 3 then I'd see green start to grow on the walls and cloudy
water abound.

I'd suggest looking at the tfp calculator to see what your FC should be, but if you get it up to 10
and at least maintain that, you shouldn't be having any algae issues. It shouldn't take much bleach
to get it up there, maybe 3 gallons of 8% bleach (guessing) then run the pump for a day.

The cold weather will keep it steady longer than the warmer times of year.
 
If the previous owner had used pucks or anything stabilized they had been adding cya the whole time. That is how that gets so far out of whack. Assuming that the cya is actually 200 ( let's not do that, dilute your sample 50% and double your result etc) and you do a 50% water change it should lower to 100. There is no CYA in your fill water. The only place that it can enter is via a human.

I say do that now. Because you can. If there is another drought next year and there is a ban on using that much water for a pool your only choice will be to find someone to come in with a reverse osmosis machine to remove cya.

With cya north of 200 it will be hard to keep enough fx in the water to be effective. Ina non swg pool closer to 50-60 is a better answer.

Sent from my iPhone using Tapatalk
 
Thanks everyone for the quick responses! I'm going to re-run my CYA with dilution and test my fill water for TA and CH levels, then report back.

Just so I know who to blame, is it possible I drove up the CYA over the past few months by putting two small bags of chlorine powder into the pool and leaving the floating dispenser in all the time (with the Kemtek tablets), or is it more likely I inherited this problem from the previous owners?
 
You added to the problem, but you didn't do it all. Every time you add a puck or granular chlorine that is stabilized with cya, it stays in your pool. You inherited and continued to add to the problem. This forum will get you on the right track.
 
JPhresh said:
Thanks everyone for the quick responses! I'm going to re-run my CYA with dilution and test my fill water for TA and CH levels, then report back.

Just so I know who to blame, is it possible I drove up the CYA over the past few months by putting two small bags of chlorine powder into the pool and leaving the floating dispenser in all the time (with the Kemtek tablets), or is it more likely I inherited this problem from the previous owners?
Click to expand...
This might help explain it. I wrote this last year.

We'll take a 16000 gallon pool, because that's what I have. On a fresh fill, prominent national pool chain recommends 2.5 pounds pf stabilizer per 10,000 gallons, which works out nicely to 4 pounds which brings CYA to 30.

With an average loss of 2 PPM/Day or 14 ppm/week, I'll have added 8.6 PPM/CYA if I used trichlor pucks perfectly. And they recommend a weekly "shock" of dichlor between 5 and 10 FC.... 2-3 oz per 10,000 gallons. Split the difference; I'll add 4 oz. CYA went up another .9.

So..by the end of week one, I have added 9.5 more CYA. It is now 39.5. Mimimum FC for that is 3, so I'm probably okay.

Week two, up to 49 CYA.
Week three, 58.5. Minimum FC should be 5, but they recommend 3 as ideal, so the pool looks a bit hazy. So I'll toss in a little extra dichlor "shock" to jack FC up to 10. Which adds another 6.4 CYA. Keeping count? We're up to 64.9 now.

That caught the algae just in time.. we had two weeks of good luck. A steady diet of pucks and 4 oz. "shock" each week only added another 19, up to 73.9 now.

Week 6 it started looking funky, so we "shocked"it once again. CYA is up to 99.3. But minimum FC to keep algae at bay is 8, and we're still holding things to 3, because prominent national chain's preprinted sheet shows that as ideal. So algae got a toehold and the pool has a bit of a tint. So we throw two whole bags of dichlor in which jacks it another 7.6 by the time week 7 is over, we're at 116.4, because we had pucks in the floater the whole time.

So...in 7 weeks, from 30 to 116.4. Let's say there are no more algae outbreaks because they sold me a huge bucket of phos-free and another of yellow-out monopersulfate "shock" Nothing but the pucks and the extra 4 oz of dichlor "shock" weekly. So the next 7 weeks added 66.5, which brings the total to 182.9 CYA.

Now if we didn't understand this and things looked a bit hazy, we might throw an extra puck or two in the floater every couple weeks, which will drive it over 200 easily.

Remember, your pool is open year-round, so even if you don't do the weekly shock, you're still adding more and more CYA with every puck. And the previous owner might well have followed that routine. Short answer is: yes, you need to drain some. I took over my pool with CYA somewhere in the 220-240 range and a drain was out of the question since we were under water restrictions. It is possible to maintain it with that high a CYA, if you use the FAS-DPD test. I've done it, but I don't recommend it to anyone. The pH test will always be questionable. Bite the bullet and drain what you can. Use it on the lawn and top off the pool with what you would have used irrigating. I also directed a rain gutter downspout to my spa. It acts as a settling basin. When it rains, I start pumping water out of the pol. The roof area that empties into the pool makes it work out to 3X whatever rainfall. My pool's average depth is 60". !" rain is 3" in the pool, which is 5% reduction of CYA and CH. Not bad! You mileage may vary.
 
Pucks and granules with trichlor/dichlor as the main active ingredient will always add CYA to your pool. Any puck or granule with calcium hypochlorite as the main active ingredient will add calcium to the pool. Your test results showed calcium on the high side as well and with a high pH of 8.0 you could develop scale on the surfaces of the pool. At this point a series of drain and refill cycles sounds like your best bet to get the pool under control.
 
Again, thanks to everyone! Richard320: the CYA saga you reposted was very helpful in understanding how mine got so high...

Speaking of which, I retested with dilution and came up with CYA = 180 to 200, which is where I thought it was. Time to drain and refill!

JasonLion said:
It would be good to measure your fill water TA and CH levels. Hopefully they are both fairly low. If either is 50 or higher you will need to adjust how you approach things a little.
Click to expand...

I tested my fill water -- both the TA and CH are 90. So what adjustments do I need to make to my approach?
 

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