SWG and chlorine levels

[doriec]

I have had my SWG now for a month, and I have algae. I have been running it 12 hours per day at 50%, with a constant 3.5 FC level. My CYA is 70. Do I need to take the chlorine level to the recommended FC level of 5? It seems those who post information about SWG's run their chlorine levels lower. Is it necessary to run the high CYA level for an SWG? Aren't chloromines zapped as they pass through the cell? Is that why some run the chlorine levels lower? Thanks, Dorie

[Poolsean]

Doriec,

Which system do you have (control system and cell size)? Do you have any warning lights or codes on the unit?
What are your Total Chlorine, pH, TA, CH, salt level, and since you have algae, your phosphate levels? Most of these you can test yourself, but the phosphate test, you'll have to take it in to be tested.

Do not use any algaecides containing mustard or yellow in the name as it may contain sodium bromide, which is not good for salt systems.
Can't say if you need to increase the chlorine level to 5.0 until we get a better idea of your overall water chemistry. Please test and report these figures back here.
Yes, it is necessary to run the higher cya levels with salt systems.
Yes, chloramines are zapped as they pass through the cell. However, if you already have a high combined chlorine level in the water, you may not be able to clear it out and a manual shock will be recommended.
Yes, you should be able to run a lower FC residual because of the "shock" characteristics of a salt system.

[doriec]

Hi Sean,
I have read many of your interesting posts. Your information about SWG's helped us choose to buy one. Here are my readings from Ben's test kit:
FC 20
CC 0
PH 7.4
CYA 70
salt level 3600--I have an aquarite for a pool up to 40,000 gal; my pool is 27,000 gal
CH 250
TA 140-I am working on this.
I had been running the pool 12 hours a day at 50 %, and have been maintaining a residual FC of 3.5. I suspect a large pool party and swimming suits worn in a nearby lake were the culprits.
Since then I have little chunks of algae on the bottom of the pool and extremely tingly water. I have been shocking for 2 days now with bleach, bleach, and more bleach. I have also been running the SWG for 24 hours at 70%. I have been checking the FC every few hours to see if I have to add more bleach . The FC level is still dropping slowly each time. this morning I still had the chunks of algae and clear bubbles on the sides of the pool. I have been brushing regularly. IS patience the key? How high should I run my FC after I get rid of the algae? I have had the pool three years and NEVER had green algae. I don't think phosphates are the problem. Thanks, Dorie

[PatL34]

Dorie,

Patience is the Key. I assume you have a plaster pool to let you go up to 20 ppm Cl.

If so keep up with the bleach to help the cell as much as possible. Is there any other source of algae, like fill water that might be problem.

Are you vacuuming to waste after you brush. This can help.

Pat

[doriec]

Pat, Thanks for the help. I have a vinyl pool. I have not noticed bleaching of the liner at the high chlorine level. I have not vacuumed to waste. I backwash to waste. My pool drains very quickly if I vaccuum to waste, and I live in Kansas and am under severe water restrictions. Today at noon my pool was at 20 FC. Five hours later it dropped to 15 FC. How quick a drop in FC is acceptable. I was in full sun today, and I see no algae now. Also, during the day, can I leave my solar cover on to preserve chemicals and shield them from the sun? Dorie

[PatL34]

With the SWCG on, it is better not to cover the are of the return jets, so as to allow the hydrogen generated by the cell to dissipate. The CYA at 70 ppm should be enough to keep chlorine without the pool cover.

By all means backwash to waste. You appear to be winning the algae battle, and as the FC starts to drop less and less, then is the time bring the FC level down gradually, at about 5 ppm per week. If you start to see algae again, bring it back up to 15 ppm and hold it until it goes. Again patience and perseverance is needed.

Pat