Is it possible to go to weekly chlorine additions?

[Steve_in_NC]

Would it be possible to raise CYA to 100 or so and just add all the chlorine needed once weekly? Will that make the chlorine last long enough to go a week?

For example, if using 3ppm per day, could 21ppm be added once weekly?

[PoolDoc]

Yes.

I've described doing that several years back, but it was one of the ideas received poorly by various folk who were here then.

There are some downsides, and it's not for everyone. For example, dealing with algae can difficult, since with CYA = 150, controlling mustard algae can require chlorine levels above 75 ppm!

However, I'd be interested in working directly with you, since I have only limited field data on what sort of problems people might encounter using this approach. To go further, you'll need:

1. A K-2006 test kit and a Hach 562227 Phosphate Test Kit.
2. Complete test results on BOTH your pool water AND the water you fill with
3. If it's well water, we'll need to do some additional tests.
4. A description of your pool (volume, type, filter type + size, pump type + size)
5. Past issues (if any) you've had with maintaining your water. (Various pools, in various locations, some times have recurring problems due fill water, nearby bodies of water, overhanging vegetation, etc.)
6. How YOU use the pool (number of users at one time, frequency, age and water-time duration).
7. How often you have to ADD more water, and how MUCH each time.
8. Information about how much PHYSICAL debris (leaves, dust, etc) your pool accumulates in a week.

The goals would be

1. Lowered chemical costs
2. 1x per week chemical service
3. Algae free operation.

Let me know if you're interested.

[Steve_in_NC]

I'm investigating. At this point, I'm not ready to do it until I understand the concepts.

I assume from your comments that CYA would need to be 150 with very low phosphates. Any other important concepts to the method? I'm considering trying the method in a small pool to see if it works first.

[PoolDoc]

So-called "chlorine shooters" in S. Cali and Arizona have done it for years, but only in concrete pools with deep ends. They'd run CYA between 100 and 150 and inject about 15 - 20 ppm of chlorine, as gas, into the deep end. "Pool Chlor" was one of the biggest of these companies.

Low phosphates is a whole other thing. The way it's marketed mostly does NOT work. If you want to do both, you probably need to learn to do low phosphates, first. Phosphate control is a METHOD, not a CHEMICAL. If you MASTER low phosphates, then you won't necessarily need to go high CYA / high chlorine to enable 1x per week treatment.

Though, what you'd probably need is 1x per week, plus a small standard bleach dose every time the pool was used. For many IG pool owners, that's about 1x per week. But if your pool is used a lot, then the protocol would have to be adjusted.

[Steve_in_NC]

The low phosphate concept is good.

However I looked at some of the products and found that they contain a proprietary mixture of rare earth metals. These compounds precipitate the phosphates which can be cleaned out by filtration. The problem that I have with this is that rare earth metals are often mined together and difficult to separate.

Some of these rare earth metals are radioactive. I'd hate to add something radioactive to my pool.

[PoolDoc]

Not sure that's really the problem with the phosphate removal process. But you know best.