Newbie needs advice interpreting first test results

[laughingboy]

Hi all,

I've just decided to take the plunge and do my own pool maintenance. A friend pointed me to this website and suggested that I get the Taylor K-2006 Complete FAS-DPD kit. I did my first testing today and have a lot of questions.

Background: I live in Tucson -- we've had continuous sunny days here. My pool is 15000 gallons, pebble tec with a cartridge filter. The water here is very hard. I've also had problems with lots of bees clustering around my pool's overflow outlet. I eventually killed them off over the course of a couple weeks with a diluted dish soap solution -- I only mention this because a good portion of what I sprayed entered my pool, so perhaps it had some effect on the pool chemistry?

I took a sample of my water to Patio Pools to have them analyze it with their Alex system as a double check on my results. Here's the comparison:


My results: FC: 0 TC: 0 pH: 8.0 TAlk: 175 PPM CH: *** CYA: > 100 PPM

Alex: FC: 0 TC: 0 pH: 8.5 TAlk: 129 PPM TH: 400 PPM CYA: 150 PPM

Other from Alex: TDS: 2600 Adj Alk: 84


Testing comments: My calcuim harness (CH) test was a complete disaster. The color never changed from red to blue. I gave up after 30 drops which were supposed to be 25 PPM each. I have no idea why this went wrong. Alex reports total hardness at 400 PPM.

I was way off on the pH. There are only 5 color comparison samples (for range 7.0 to 8.0) so I don't know how I'm supposed to get a good reading for pH > 8.0.

Similarly with the CYA test: The mark spacings look logarithmic and only go from 30 to 100 PPM. The fluid level was below the 100 line so I knew I was well above 100 but it's hard to say how much.

I knew my total alkalinity would be high so I was using a titration with 1 drip equaling 25 PPM.

Is it a good idea to use the CYA alkalinity adjustment? The Taylor book recommends it but says that it is controversial. The Alex system uses it. Based on the readings I took (using, say, a CYA of 120) I would have come up with adjusted Alk of 132 -- pretty high. Alex says I should be adding baking soda because the adjusted alk is so low!

Anyway, here are the recommendations Patio Pools gave me:

1. Add 10 lbs of Balance Pak 100 (baking soda)
2. Add 4 pts muriatic acid
3. Shock with 2 bags of "Burnout 35"

How does this advice sound to you? Can I shock with Clorox laundry bleach instead? If so, how much?

Also, I've it's been suggested to me that I at least partially drain the pool. My pool service (which I discontinued) suggested I drain because of the high CYA levels. Conversely, Patio Pools says the CYA is on the high side of "in range" but says I might want to drain because of the high TDS levels. I'm also wondering if I might have a chlorine demand problem because I shocked the pool with Burnout just a couple of weeks ago. Might draining help with this? Finally, somebody else told me that it's a bad time to drain the pool because of the high daytime temps -- the pool itself could be damaged from the heat with the water level low. So I don't know what to do about this.

Thank you very much to everyone who can help me out with my questions!!

Mike

[Watermom]

That high of a CYA is gonna be a problem. I'm surprised you don't have a green pool with high cya and no chlorine in there. You have a low water table there, right? If it were me, I'd do a big drain and refill. If a place has a high water table, you don't want to totally empty a pool or it can pop out of the ground. This is not such a problem when the water table is really low. If you aren't sure, just don't drain it all but drain a lot of it. That will get your cya down to a more manageable level and then we'll go from there.

Yes to using bleach. It is what most of us on the forum use for our source of chlorine.

[laughingboy]

Thanks Watermom, I'll be looking into draining the pool ASAP.

[polyvue]

I've also had problems with lots of bees clustering around my pool's overflow outlet. I eventually killed them off over the course of a couple weeks with a diluted dish soap solution -- I only mention this because a good portion of what I sprayed entered my pool, so perhaps it had some effect on the pool chemistry?

Testing comments: My calcuim harness (CH) test was a complete disaster. The color never changed from red to blue. I gave up after 30 drops which were supposed to be 25 PPM each. I have no idea why this went wrong. Alex reports total hardness at 400 PPM.

I was way off on the pH. There are only 5 color comparison samples (for range 7.0 to 8.0) so I don't know how I'm supposed to get a good reading for pH > 8.0.

Similarly with the CYA test: The mark spacings look logarithmic and only go from 30 to 100 PPM. The fluid level was below the 100 line so I knew I was well above 100 but it's hard to say how much.

Is it a good idea to use the CYA alkalinity adjustment? The Taylor book recommends it but says that it is controversial. The Alex system uses it. Based on the readings I took (using, say, a CYA of 120) I would have come up with adjusted Alk of 132 -- pretty high. Alex says I should be adding baking soda because the adjusted alk is so low!

Also, I've it's been suggested to me that I at least partially drain the pool. My pool service (which I discontinued) suggested I drain because of the high CYA levels. Conversely, Patio Pools says the CYA is on the high side of "in range" but says I might want to drain because of the high TDS levels.

I agree with Watermom and the pool service that suggested that the pool should be drained because of high CYA -- not due to high TDS (but you'll likely reduce TDS as well). Whatever dish soap that survives the drain/refill will be oxidized by the chlorine you'll apply to the water.

In Tucson, I'd think that the concern about draining a pool during summer is less about ground water and more about plaster preservation. But you're not planning on leaving it empty for the summer so don't see this as a problem. After the pool is drained, just start refilling.

The end point of the CH test can be subtle and therefore, a bit tricky. Practice makes perfect. This article describes the CH test with photos, but in my testing the end point is closer to lavendar than the blue they show.

Your Calcium Hardness (CH) may be on the high side when you refill but that can be ameliorated by maintaining a lower Total Alkalinity (TA) and keeping pH in check (always lower than 8.0). I believe that the advice to add bicarbonate of soda was faulty. Isolating carbonate alkalinity is useful mainly in determining the Saturation Index but I wouldn't worry about any of this until you've refilled and added some liquid chlorine to the pool. Retest the refilled pool and use this as a baseline.

If your pH starts out at 8.0 or higher, lower it with small doses of muriatic acid (MA) until it registers on the pH test at a lower point. For the CYA test, you can dilute the sample (50:50) with tap water, then double the result for a rough estimate.

[laughingboy]

Thanks for the advice and testing tips polyvue. I'm refilling my pool now -- see my other thread for my continued pleas for help :-)