Considering UV for a new outdoor pool.

[Symon]

Hi,

I am quite new to this pool stuff and to this forum. Rather than ask a question, I have been following many similar posts to the issue I am having and first came here as I was doing research on a UV system that looks like it will make pool care less time consuming.

I am dealing with my first algae bloom, despite my best efforts to keep things clean and a fair bit of money spent on pool store chemicals.

Either way, I would be grateful if you could rescore my registration, so I can read further into the forums, particularly about UV vs salt water and, as a result of being here, alternatives to pool store chemicals.

Thanks,

Symon

[Watermom]

Symon, until your registration is completed, if you will log out first, you will be able to see the rest of the forum.

Tell us the details about your pool ---- type, volume, size of pump, type of filter, any other equipment you have. Also, tell us exactly what you have added to the pool meaning actual ingredients and not just 'shock.'

We also need a current set of water testing results taken with a drops-based kit. The kit we recommend that everyone get is the Taylor K2006 (test kit link in my signature below).

Reply back with requested info and somebody can try and help you out.

Welcome to the Pool Forum!

[Symon]

Thanks for the welcome, Watermom!

Here are my details:

We are located in Southern ON, Canada. The pool is inground and a rounded, rectangular 40x20', approx. 125,000L or 32,000 gal(?) with a vinyl liner. It has a Hayward Superpump 0.75HP with only 1 speed seting. It is on a Hayward Pro Sand Filter with 53GPM capacity and also has a Hayward CL220 chlorine feeder, using 3" pucks.

Current readings on an Olympic drops test kit are: Br 2.0, Cl 1.0 and pH 7.2, although when we took a sample to the pool store, they said we had no chlorine in the water. I am probably going to order the Taylor 2006 kit today, as I just read about some of the other indicator on the forum (that was why I had not logged off lol).

Over the last 24 hours, we have added:

1 L of IPG Algi-pro 60 Algicide two times, approx. 12 hours apart
Shocked pool 3x with 1.5kg IPG Shock Plus Sanitizer.
Added 2kg of IPG Alkalinity plus sanitizer
Added 500g of Aquapro Pool Protect pH+

All of this on pool store recommendations (I am seriously considering buying shares in IPG BTW)

The algae bloom that we are fighting has dissipated somewhat and the sotre has told us to add another 2kg of stabilizer tonight, then flash again.

I should note that all of this happened after a great deal of rain and then a very hot spell, while the solar blanket was on. The algae itself is in the water, with a little yellow algae on the stairs and in the shadier parts of the pool .

Thanks so much for any help! Back to reading about BBB pools now (I am hoping the 3rd B does not mean bulldozer...)

[BigDave]

... particularly about UV vs salt water...

UV systems for outdoor pools are pretty much redundant. There's plenty of UV from the sun. In fact, UV destroys chlorine and chlorine is the most effective and efficient sanitizer you're likely to find. Salt water (more correctly Salt Water Chlorine Generators) are a convenient way to chlorinate a pool but not usually cost effective.

I recommend that you spend your first season with the pool learning to control it with the BBB (not strictly Bleach Borax and Baking Soda) method taught here. You can always have a SWCG system installed at a later date and by then you'll know how to operate the pool.

[Symon]

Thanks for the response Big Dave.

I got interested in the UV process because we use one at our cottage to prep lake-drawn drinking water after a sand/rust and then an activated charcoal filter. The water becomes potable after the process (had it tested), so I was interested in thoughts on its use in a pool. It seems to limit the need for chlorine from what I have seen so far.

Salt water is on my radar too, although my understanding of the process is limited and it seems to be a bit of a misnomer, as what it seems to do is create chlorine.

I am definitely going to implement a BBB system for the time being as the price tag on SWCG and UV is too high for me right now (and heck, the price of bleach is RIGHT!)

[BigDave]

Sanitizing potable water is different from sanitizing pool water. UV systems can only kill pathogens that are passing through the UV system at the time, they don't kill anything in the pool. Chlorine, on the other hand, is in the pool ready to kill pathogens when they are introduced. No one is completely clean, pool sanitizer must kill the bacteria that washes away from the far end of a swimmer's GI tract before it gets to the near end. UV systems can never do this.

UV systems have a place but not in outdoor pools. That said you can find someone willing to sell these systems with claims along the lines of "reduce the use of Chlorine" and "lets you run lower, safer, chlorine levels". The first reason is just plain bunk, UV destroys chlorine so it's just not possible that it could reduce the consumption. The second reason is worse than bunk, it implies (or supports the notion) that chlorine is "bad", it is not. It also encourages a dangerous reduction in sanitizer level that may leave swimmers very sick.

Please reconsider the notion of using a UV system for an outdoor pool. At best, it lightens your wallet; the downside can be much worse.

[Symon]

Exactly the discussion I came here looking for, thanks Dave!

[BigDave]

Good, you'll need the money you save on the UV system for the inflated Taylor kit prices north of The States.

[PoolDoc]

I was doing research on a UV system that looks like it will make pool care less time consuming.

I am dealing with my first algae bloom.

so I can read further into the forums, particularly about UV vs salt water

membership upgraded.

Regarding your pool issues, I want to respond to some of your questions, since UV posts seem to have taken an upturn recently. Some of this has already been covered, but I wanted to collect it in a single post.

1. I am one of VERY few who have actual field experience with an effective UV irradiation system for pools.

2. UV systems do NOT sanitize pools; at best, they may sanitize the water in the irradiation chamber.

3. UV systems have little or no effect on algae.

4. In all but the most extreme cases ($$$$), *outdoor* pools ALREADY get more UV from sunlight than they will from an added UV system.

5. The ONLY legitimate applications for pool UV systems I know of are (a) to reduce complex chloramines in heavily used indoor pools, OR (b) as part of an exotic treatment system on luxury indoor pools, to eliminate detectible chemical use.

6. The system I worked with was the later case, and used UV + hydrogen peroxide + polyquat to make chemical use undetectable to swimmers. I swam laps in that pool, and can tell you it performed exceptionally well with respect to that goal. BUT, it was very expensive and rather high maintenance. To give you an idea of what sort of location it was, I discovered that the Greek amphora-style vases that were on the deck had cost over $120,000! Fortunately, I did not break one, when I nearly knocked it over with my tool box!

7. There is no legitimate UV vs salt comparison as a standalone pool treatment system. Salt water chlorine generators (SWCG) provide an effective means of sanitizing pools continuously with chlorine. UV systems don't provide an effective means of sanitizing anything, except the gallon or so contained in the contact chamber. Chlorine is an effective oxidizer of pool wastes; UV is not. UV + chlorine *is* an even more effective system, than chlorine alone, but sunlight provides more than enough UV for this effect to take place on outdoor pools.

8. UV systems, even where effective, are still rather experimental, and are only likely to work well when installed and serviced by someone who is far more expert in water treatment than 99% of the pool guys out there. Such a person is unlikely to be a UV promoter.

9. Even where effective, UV systems will NOT reduce pool maintenance, especially compared to a pool operated with the BBB method taught here. UV systems should only be used where the benefits (say on a commercial indoor therapy pool) outweigh the costs and additional maintenance.

10. To get rid of algae, add PLAIN household bleach till you read and hold a DARK yellow OTO level (cheap OTO/phenol red drops kit purchased locally), and keep those levels for a week after all traces of algae are gone.

11. Read the Best Guess page, linked in my signature, for an explanation of what's going on.

12. After you've read that page, order a K2006 test kit (Amazon link in my signature -- but in Canada, this site -- http://piscines-apollo.com/ -- may be your only source) so you can manage your pool's chemistry easily and effectively.

I got interested in the UV process because we use one at our cottage to prep lake-drawn drinking water after a sand/rust and then an activated charcoal filter. The water becomes potable after the process (had it tested), so I was interested in thoughts on its use in a pool.

Treating a once through system with no added 'dirt' load cannot be compared with treating a recirculated system, with constantly added 'dirt' (swimmers, etc.). The fact that you are treating for rust suggests that the lake may be acidic, which in turn suggests it may be clear, nearly sterile water ALREADY.


Good luck!