When do you add a maintenance dose of algaecide?

[famousdavis]

So my local pool company sold me some polyquat and said to use 6oz. weekly on my 16K gallon pool, as a preventive measure. They further said to pour the algaecide into the pool following superchlorination (I use the Boost setting weekly on my SWCG).

Tonight I actually read the instructions on the bottle of algaecide. It says to add the algaecide 8 hours after superchlorination -- rather than immediately following superchlorination, like what my local pool pro said to do.

Is there a "right" time to add algaecide? Does it matter whether I add it right after the Boost cycle (which lasts 24 hours) finishes, or should I wait 8 hours after the Boost cycle finishes (and why would it matter if I did wait)?

Thanks for the answers here.

[waterbear]

If you are maintaining your FC at 5% of your CYA then the need for 'preventive algaecide' is moot. However, polyquat does cause a temporary drop in FC levels and shock levels of chlorine break polyquat down (yet the break down products still maintain some activity against algae).

[famousdavis]

So maybe the reasoning for adding polyquat after 8 hours is it doesn't diminish the shock level of the FC (allowing it to kill whatever may be lurking in one's pool), and the polyquat is just a second punch in the gut after the first punch of chlorine shock.

I'm apt to add the polyquat into the pool weekly as a maintenance thing. The Taylor K-2006 info booklet says to consider maintenance doses of algaecide as an insurance policy against a big algae problem. I'd rather reduce my chances of having an algae problem than accept a somewhat greater risk by not adding the algaecide. After reading through this forum category in particular, it sounds like algae can appear pretty suddenly. From my days of owning an AG vinyl pool, I remember plenty of times that a green algae bloom would occur if I failed to keep up with the chlorine regularly (which invariably occurred at some point during the summer). It would bug me much worse to have an algae problem in our brand-new, in-ground pool.

[Watermom]

For what it's worth -- I never use algaecide. I watch my chemistry closely and make sure I maintain adequate chlorine. Thus, no algae. If you are diligent about testing and maintaining proper levels, then you really don't need algaecide.

[famousdavis]

Watermom, at what levels do you keep your free chlorine? And do you shock your pool only when you've got > 0.5 CC, or do you shock regularly? Finally, what's your pool temperature?

Thanks for your 2-cents. I'm learning, making decisions on how I want to maintain our new pool. This forum has been very helpful!

[Watermom]

My pool is too hot right now --- about 92 or 93. We've had a string of hot days around 100 and extremely high humidity. Cooler today. "Only" 95. I'll leave the solar panels off and the solar cover off for a few days and drop the water temp a few degrees. Fortunately, we swim in the evenings rather than the daytime, so it actually feels pretty good. But, that would be too hot for a midafternoon swim on a hot day!

I keep my FC between 3-6ppm and I seldom shock my pool. I think I did one time this summer and that was because there were a couple of days where I thought somebody else was adding bleach and they thought I did it. So, my FC dipped too low and I shocked it. That doesn't happen too often. There are some summers where I never even shock the pool at all. It isn't necessary to shock as long as your CC is no greater than 0.5ppm and your FC stays in the range needed based on your CYA level.

Glad the forum has been helpful for you.

[chem geek]

Polyquat is also a mild clarifier so if you are shocking to kill algae then the Polyquat can help clear the pool faster IF you have poor filtration such as with some sand filters. Of course, adding some DE to a sand filter is another way to improve filtration and if one truly wants to use a clarifier there are stronger ones one can use (such as GLB Clear Blue). In general, clarifiers are not needed.