new guy with testing and numbers questions

[bob.lehardy]

Aloha everyone, I'm Bob, and I live with my wife on Kauai. Two years ago, we purchased a home that came with an in ground pool, and we have been enjoying it, but I'm trying to figure some things out. We like our pool, but are only in it about once a week or so, so it gets little use.

This is Hawaii, and we have palm trees and other trees all around, so we get organic material that daily finds its way into the pool.

For the past two years, I've tested the water weekly with basic test strips, and have added some chemicals to keep things in range.

The SWG saline light is normally solid green, indicating salt "in range", and a few times it turned red, I've turned the SWG off, added one bag of pool salt, allowed it to circulate for a day, turned on the SWG - if green, life goes on, if red, turn it off, add a bag, wait 24 hours, repeat.

The pool came with a heater, but I have never turned it on. It shows a pool temp of 86 degrees F just from the sun.

I have been running the pump at 1900 RPM, from 9 am - 4 PM (7 hours) daily.

The SWG was set at 60% for most of that 2 years, but based on some recent numbers, I've dropped it to 40% (will discuss that in a moment).

We have had an unusually wet year. In April, for example, our area received 10 inches of rain overnight, and 14 inches in two days. During that, I drained the excess water to waste several times, to keep it from overtopping. The pool was cut into a small hill, and along the back wall there is a 3 foot tall black lava rock retaining wall. During that rainstorm, groundwater was running into the pool. After the rain stopped, we vacuumed the debris, cleaned the pump traps and skimmer, and backwashed the filter. The water was a little cloudy then, but cleared within a week or so.

Since then, we've had several days of more heavy rain, but not that heavy.

So, a few weeks ago I found this site, began reading and learning. I bought a TFT-100 test kit, and have a Taylor saline test kit on the way. I have done all of the TFT100 tests twice now, with a chemical addition in between. Here are the results so far:

	Targets	9/11/2018	9/14/2018
FC (free chlorine)	4	7.5	9
pH	7.2-7.8	8.2	7.5
TA (total alkalinity)	60-80	160	150
CH (calcium hardness)	350-450	250	125
CYA	80	58	59
Saline	3600	Not tested	Not tested
Temp		84	86
CSI		0.8	-0.19
Comments		added 32 oz muriatic to lower pH

On 11 Sep, pH tested high, so I added the amount of muriatic acid recommended by PoolMath. Retested today, and pH is good. What causes pH to go up?

I do not know the exact saline yet, but the light on the SWG is green. Once that test kit arrives I can provide a number.

FC seems high, so that prompted me to dial the SWG output down to 40%. How long might it take that to come down? Or is there something else I should do to bring it down?

I'm adding stabilizer tommorow to bring CYA up.

TA is high, CH is low. Is one a priority over the other? And do I work on them one at a time or together?

thanks for the great site and the advice.

 

[mknauss]

Welcome to the forum! :handshake: Great job on getting a quality test kit!

I would not focus on TA. As your pH hits 8, lower it to 7.4 and your TA will drop. pH rises primarily due to aeration with your high TA. Aeration occurs in the SWCG plus simply rain hitting the surface increases the pH. I am curious how your TA got to the level it is. Had you been adding any baking soda? With rain being what you add to the pool, your TA I would think be quite low.

I would add some calcium. All the rainwater you get your CH will drop. For the longevity of your plaster, I would suggest getting the CH to 300 or so. You will probably have to add calcium on occasion based on rain water dilution.



I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.

You may also want to get the Pool Math app.

- - - Updated - - -

CYA -- not sure you need to add any. Your SWCG is easily maintaining your FC. And your current CYA of 60 (round up) is OK,

 

[Dirk]

I did an experiment once, collecting rain water off my roof to see how that would work in my pool. I was very surprised at how the rain runoff picked up unwanted stuff off the roof (the particulate I expected, but the chemical stuff I hadn't). So I abandoned the effort. I would think lava-rock filtered rain could have an equally negative affect.

Pools and their surrounding structure or landscaping are supposed to be designed to keep any runoff out of the pool water, but I suppose that much rain is going to do what it wants, right? Do you have any way to improve the runoff from the lava, to channel it somewhere else besides into the pool? Cleaning up the residue is one thing, but keeping out the chemicals is important, too.