Light Green Pool

[Hobo1]

Our pool is a 3 year old, 9,600 gal GUNITE (with attached Spa), located south of Tucson, AZ . . . approximately 5 - 10 miles from a large, active copper mine. We have a frog system for chlorine. The cleaning system utilizes turbo cleaning heads and activator valve. The source water is very alkaline. We first noticed on the pool floor what we thought were particles from the pumice stone we were using to clean the tiles (we had quite a buildup of scale on the tiles) . . . within days, we began noticing "something" on the pool walls. On Jun 27th, we adjusted the pH to 7.5. On Jun 28th, we added the monthly scaler inhibitor (16 ounces). On Jun 29th, we took a water sample to the pool store with the following reading: CYA = 151, TC = 10, Free C =10, pH = 7.3, TAlkalinity = 180, Adj TAlkalinity = 135, THardness = 296, Manganese = NO, Copper and Iron, not tested. Water was clear, Cartridge filters cleaned the day before the sample -- at that time the water appeared blue and clear. After taking the water sample, we added Backup (12 ounces). That evening the water had turned green & green scum was being swirled by the turbo heads on the surface of the water . . . scum attached itself to anything floating. We have brushed sides of pool for 4 days regularly . . . water has stayed light green and clear (not cloudy). After reading the forum, yesterday (Jul 5) we cleaned the filters again and pulled the chlorine frog out of the system and shocked the pool using 2 gals of 6% Chlorox. This AM the pH = 7.6, Free Chlorine was 10+ based on observation (can't read higher than 5 but know what the color does after 5), pool is still light green in color, but clear. Scum is minimal to gone. We are at a loss as to what to do next . . . ANY COMMENTS . . . ANY HELP WILL BE GREATLY APPRECIATED. Hobo

[Backglass]

I find it interesting that being so close to a copper mine your pool store didn't test for copper!! A pool turning green upon shocking is a sign of copper in the water (that and green hair ). You should have them test for copper or just get some sequestrant anyway to be sure.

Your larger problem is that with a CYA reading of 151 (VERY high...50 is the max in a non-salt pool) you would need a chlorine level of at least 47ppm+ to shock and a target FC reading of 13+ just to stay sanitized. Your completely off chemgeeks "best guess" chart so those numbers are probably even higher!

You must get your CYA down or your problems will just continue/get worse. CYA is like sunscreen for chlorine. It keeps he sun from degrading it, but it also locks it up so it doesn't work as effectively. A little is good. A lot is bad. Unfortunately the only reliable way to bring it down is dilution...you need to drain some water (a foot or two), refill with fresh and re-test. You also need to stop using stabilized chlorine (pucks/etc) immediately as this is where it's coming from.

To check a reading higher that 5 dilute your pool water 50/50 with distilled water, then multiply the color reading by two. (1:4 and multiply by 4, etc).

[Hobo]

Backglass. Thank you for your reply. Will check the free chlorine using diluted method. Will follow your instructions. Thank you very much. Hobo

[Hobo]

Backglass: Drained 2/3 of pool last night . . . refilling completed . . . water is clear . . . can see bottom . . . once I turn on system HOW LONG SHOULD I LEAVE IT CIRCULATE UNTIL I TAKE THE FIRST WATER SAMPLE? At this point, we have removed the chlorine cartridge from the frog . . . . I will also have our "pool store" test for copper.

Hobo

[Backglass]

It depends on your pump and pool size but if it ran overnight by all means test and see where you are at. You should be able to use MUCH less chlorine.

2/3 of the pool?! You did drain an awful lot at once. You might be having to ADD cya if you went overboard. But with levels that high you are probably fine.

[Hobo]

Backglass: We ran "the 2/3 water new pool" overnight . . . took a sample into our pool store . . . test results were: Total Chlorine 2.3; Free Chlorine was 2.3; pH 8.1 (not surprising since source H20 is very alkaline and we had not adjusted prior to visit); CYA was still 151; TDS went from 3,200 to 1,300; we tested for Copper -- 0.2 results. Yesterday we added 1 QT of acid; the Free Chlorine was 3.0; added 11 oz of Algae All 60. This morning the results were Chlorine 3.0 and pH 7.6. The green color is gone . . . the water is blue and clear. We think this is good . . . do you?

To add a bit more "fun" to this experience, the replacement pump which was installed Dec 26, 06 (on a pool that was less than 3 years old) sounds like it is about to give up the ghost! Although the first pump was covered by warranty . . . the replacement pump, I am told, is NOT! This pump appears to be wired correctly; it very hot to the touch; is installed on a slab; and totally exposed to the elements, i.e., the hot desert sun. Bottom line: From reading in another section, I guess I should have shaded the pump from the UV, but didn't. It has been an interesting "pool summer"! Thanks for all your help . . . your comments are very much appreciated. I am learning. Hobo