New member with Florida pool

[Fuldo]

I've been watching this site for more than a year now and have learned much from it. I bought a house in Florida 5 years ago with a mid size gunite pool that had been neglected for years, in fact it was untouched for at least two years. You could say it was a pond when I first saw it. We've brought it back to where it's almost perfect, well worn plaster is the biggest defect now. I had problems with algae until about 9 months ago, even with professionals caring for the pool for the first three years I owned it. It turns-out the primary problem was high (100+) CYA. A secondary problem was a large plaster waterfall structure that I now believe harbored algae inside and out. The pool was drained more than half and the waterfall removed about 9 months ago. After refilling, some tweaks and using only liquid chlorine the water is now perfectly clear and requires little attention. I also had some problems with "green dust" coming from some pool surfaces, that has completely disappeared as well.

My only concern at this point is that the PH tends to rise constantly. I'm putting in about 6 oz of acid each day to hold the PH about 7.5. The odd thing is if left alone the pool PH tends to stabilize at about PH 8.1 and stay there. I have marble chips around the pool coping about 3/4 around the pool and I'm wondering if that may be partially to blame. Any thoughts or suggestions would be greatly appreciated.

 

[kimkats]

HI! So glad to hear you got a good handle on your pool for the most part. From Pond to Pool is quite something to pull off! Had to feel good when you were able to walk out and look at your pool and NOT see any green!

If you have been reading you know I am going to ask how you are testing your water then ask you to post a full set of results. I have a couple of ideas on your PH problem but need all of the data to see if my ideas correct.

Kim

 

[Fuldo]

I bought a Taylor K-2006 FAS-DPD kit in early spring this year. This house is a second home and we come and go. Largely gone in the summer and we have a relative maintain the pool when we're not here and he uses the kit for CL and PH when we're gone and adjusts accordingly as well as vacuuming and water level adjustments. When I'm here, as now, I maintain it myself and check it every two days or so. The CYA was sky high in the spring but after a half drain and liquid chlorine diet for about 7 months now the CYA has drifted down to probably 20-25, it's hard to tell because the kit won't read that low. Lots of rain water the last two months including one hurricane that diluted the CYA more than I wanted. Last week I added the first chlorine puck since spring thinking it would raise the CYA some.

Recent readings:
CYA: 20-25 (estimate, my goal is 30)
FC: 2.5 (I let it drift down to 2.0 this time of the year and then goose it to about 8.0)
CC: 0
PH: 7.5
TA: 100
CH: 320

 

[kimkats]

Good job! I see what I thought I would see.....look at your TA....it is a little high. Saying that I do need to point out each pool is different in where they like their TA/PH.

I would like to see you get your TA down to 80. Once you do watch your ph and see if it is happier.

I am on my phone so cannot give you a link. Please do a search for lowering TA in the white search box at the top of this page.

Kim

 

[Fuldo]

Most sources I've seen suggest TA about 100. In fact, after returning home after 10 weeks away it was 60 and I just bumped it up to 100 about a week ago. It tends to drop so I thought that might be a good place to be after raising it. The high PH problem has been a curse for a long time, even with low TA count.

 

[kimkats]

Here is a link to the levels we reccomend here at TFP:

Pool School - Recommended Levels

Notice that most of them have a range. That is due to knowing each pool and area is different.

We tell people adjust their TA in increments of 10 and hold it at that place for a week or so to see what the PH does.

Another question for ya....you say your PH tends to hold at 8.1 if left alone. My PH test only goes up that high. Are you sure it is not creeping up higher and you don't know it?

Do you have any water features that splash the water? Do your returns roll the water when the pump is on? All of these can also cause PH to rise.

We will keep working on this puzzle until all of the pieces fall into place and your pool is even more Trouble Free!

Kim

 

[Fuldo]

Thanks for the support and the reference to the recommended levels. I've seen that chart before but not recently. I've been using the national guidelines shown in the Taylor manual for TA and they suggest 80-100. The TFP guideline for my plaster pool is 70-90+. I wonder why there's a difference. My pool tends to drift down in TA over a number of weeks so when I adjust it I tend to go a little high figuring it will drift down anyway. It seems to seek lower TA over time just like it seems to seek higher PH constantly. I've never had any physical problems often associated with high TA such as scale or cloudy water so I figured I'd keep it fairly high to help reduce plaster erosion considering the amount of plaster is already marginal. I'll let the TA drift down and keep it a little lower and see what happens but based on previous experience with this pool I suspect there will be no noticeable differences relative to PH drift.

As you probably know, my test kit only reads to 8.0. I've been extrapolating the 8.1 value based on both color shade and the amount of acid required to shift it back to 7.5. I've never let the pool sit for more than a few weeks without checking and correcting the PH. Durations that long only happen when I'm not home and a relative is maintaining the pool in my absence. It would be interesting to see how high the PH would go if left unattended for a longer period but I'd be reluctant to do that.

I do have some spray jets but they are never used, especially this late in the season. Some, maybe all, of the original eyeball jets had rather small discharge holes, I think they were 3/8 inch diameter. They were causing the back pressure to be rather high (13-14 PSI) even with a new filter cartridge (Pentair CC100). There are only four discharge jets, two near each end of the pool. I drilled-out the eyeballs with smaller holes so all discharge holes are now 1/2 inch diameter. The back pressure when clean is now 11-12 PSI, I figure this is more flow, better circulation, less strain on the one-speed 3/4 HP pump and less electricity consumption. The jets are aimed slightly downward and almost straight-out from the walls, angled just enough to cause a slow whirlpool effect. I couldn't find much information on sizing and adjusting return jets so I used my best judgement when I reconfigured them.

I still wonder if the marble chips around the coping may be at least part of the cause of rising PH. Has anyone ever noticed a problem like that?

 

[zea3]

I doubt the marble chips are the problem. TA and pH are tied together, just about anything you do to change one affects the other in some way. Some chemicals affect one value more than the other. Our experience with the thousands of pools our members manage, is that each pool has a "sweet spot" where the TA should stay in order for the pH to remain stable. We have not isolated all the factors that influence where that sweet spot is, but we do know it is not the same for each pool. Try lowering the TA to 80 and then track the pH for a couple of weeks. If you see the pH rise up to 8.0 try lowering the TA to 70.

TFP doesn't always agree with the pool industry's recommended ranges (CYA and FC being an example). If your pH is not stable with a TA of 100 then 100 is not the correct TA for your pool. When pH consistently rises and there is no SWG or water feature aerating the water, lowering TA is almost always the answer.

 

[Fuldo]

I just performed a few retests:
FC:2.0
PH:7.5
TA:70

The FC has been slowly drifting down at a rate of about 0.5 per day. I added about 1/2 gallon of liquid CL after this reading, that should bring it up to about 6-7.

The 7.5 PH is right where I wanted and expected it after adding 12 oz. of acid yesterday after PH was read at 7.7

The TA has dropped from 100 to 70 since ten days ago. Twelve pounds of calcium chloride was added 9 days ago to bolster the hardness, that may have influenced the TA reading somehow. Other than that only 102 oz. of acid has been added over those same ten days except for about 1-1/2 inches of rain water. That's an average of 10 Oz. of acid per day to keep the PH in check. That seems like a lot. I'm not sure what to do next, perhaps add a little more baking soda to get the TA up to 80 or so?