Aloha!

[wcvresmgr]

NOTE for all respondents: This is a COMMERCIAL pool in Hiwaii! Both facts are relevant.

Aloha All,

Firstly, lots of info on the forum and great resources.

My problem- FC levels falling

POOLS-
-50,000 gal. outdoor pool
- 2 Triton II TR-100 sand filters
- pumps run 24/7 at 2500-3400rpm (2 Pentair 3hp vrs+svrs motors)
-lots of sun exposure
-swim load may go from 45persons/day to 300. (Vacation rentals on property with over 100 homes)- no animals
-located in hot-dry dessert like climate (average high temp is in the 80s all year long)- yes we even have some cactus that grows around here.
-pool used all year long
-pool tested atleast once everyday with Taylor kit-2005C- seems to be working good for us, so no complaints on the kit yet..


-35,000 gal. outdoor pool- has a 1 1/2' deep kiddie section thus serving more as a kiddie pool
- 2 Triton II TR-60 sand filters
- 1 Pentair 3hp vrs+svrs motor running at 2500 rpm 24/7
same exposure, swimm load(although probably worse since majority are kids), location, tests.. all the same..

HISTORY-
50,000 gal pool was just converted from trichlor pucks/dichlor granuels to the BBB method.

Prior to the conversion-
-CYA 300. Using the tester- the dot dissapeared by dropping it only 1/4" under the water line..
- FC could never hold a 5.0 even if we threw in 4 3" pucks per day.
- PH always low & having to throw in pounds of soda ash every day. PH average 7.0- our goal 7.6
- TA always sky high. 120 - 140
- Water clarity totally sucked. Had a green tinge in the water no matter what we did.. Brush, vacumm etc..
- Vacationers complaining like crazy..

- DUMPED 3/4 OF THE WATER

Start-up-
- CYA down to 60
- FC at 0. Brought it back up to 10 using 5.25 gals of 10% sodium hypochlorite.(Used the pool calculator to calculate). Currently buying the liquid chlorine at Home Depot- KemKlor 10% SH @ $9.00/box containing 2 gals.
- PH sitting at 7.8-8.0
- TA sitting at 110 - 120

Presently-
- CYA at 110. Brought stabilizer count up slowly to see if I could recognize a difference in FC usage.. but was not really able to- maybe a little..
- FC trying to hold it at atleast 8.0, preferably 10.0 since the usage fluctuates. But I'm having to dump in 4 gals a night to bring it back up. NOTE: CYA is at around 110.
- PH at TA sitting still as noted prior.

PROBLEM-
I seem to have a FC drop on average around 5ppm per day (sometimes even up to 7ppm!)even at such a high CYA level. I'm having to dump about 4 gals a night to bring it back up. As you can calculate the cost- 4 gals per day @ $9.00 per box.. thats $540 a month for chlorine which is about 4 times as much as we would spend using trichlor/dichlor. I hate to bring the CYA count up further as I have not read about any other techs doing so on the forum (please let me know if there is so I might feel more confident in doing so). I just dumped a whole lot of water, although it didnt cost very much, but what a headache to do.. Anyhow, I would hate to have to dump water again due to a screw-up in raising the CYA more. As I read more on the forum- thats really the only way to tell. My question is this normal to have such a drop? getting into this, I thought that I would only need to dump a gallon every other day or at most everyday, was that asking to much?

Also, Being on an island in the middle of no where makes it pretty hard to get cheap chlorine. There was a thought about bringing in commercial bulks of the harsh stuff- gas & high concentrations of SH. Of which would cost more than "an arm and a leg" and we would most definitely defeat the purpose of savings. I'm beating my head against the wall trying to find a simple way to keep everything balanced right, keep costs down, and keep us from going awol.. Im to the point of switching back to trichlor/dichlor since it is cheaper (one 5lb. bucket per pool per month at a cost of $290 total) and just dumping the water anuually at a cost of about $450 per year.

Any advise would be greatly appreciated!

[wcvresmgr]

Update:

Here's my findings-
9/12/11 @ 10pm-
Actual FC- 2ppm. Dumped 512oz of 10% bleach to bring it to 10ppm.
- note: water was as clear as can be. No cloudiness.

Tested 9/13/11 @830am-
Actual FC- 6ppm.

Findings-
The pool size was said to be at 50,000 but was never for sure when I came onboard. In doing the calculations, if I had an actual FC of 2ppm and after dumping 512oz. of 10% bleach it was raised to 6ppm- that would mean that we have a 100,000 gal pool on our hands! In using the pool calculator I was depending on the gallon size to be right and assuming that was the amounts of bleach I needed to add at night and not checking the following morning to be sure of the levels- As I said I ASSUMED. This would also explain why the FC count was so low previously as we were not even bringing it up to where it should be(using the best guess chart). I know there could be some inconsistancy due to junk in the water killing off the CH before the end of the night, so in that case, I will be doing the same test for the next 3 nights to give me an average. I will post my findings.

Thank you,

Zach

[PoolDoc]

I'll try to respond more, tomorrow.

But two points:

Unless the 10% bleach is being MANUFACTURED in Hawaii, it's VERY unlikely that your 10% bleach contains 10% bleach. To do so, it would have to be either (a) high purity bleach, OR (b) refrigerated on the boat from the mainland, OR (c) brought in air freight. (A) is possible but uncommon; (B) & (C) are almost certainly not true.

The reason: regular bleach, above 7%, breaks down pretty quickly at hot temperatures, with rate dependent on concentration, metal content (iron & nickel), and temperature. 15% bleach can go to 7.5% in a week at temps above 90 degrees.

Secondly, commercial pool chlorine loss is often mostly a function of how many sweaty, oily bodies go into the pool per day. This chlorine demand is somewhat independent of gallons.