algacide vs bleach

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Pogo

Pogo

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May 8, 2009
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EDIT 6/14/13- In light of the information received below, I have decided to not fool around with an algaecide at all.
I will continue with my liquid bleach treatment. It's been working so far and now my wife is convinced thanks to you all.
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Howdy all, I need some enlightenment...

Last year, I kept the pool clear pretty much just using ye olde Clorox from Wally's, no problem. Now, we get our other pool chemicals from a small, family owned (3 generations now) pool store. They beat the heck out of the "super stores" even if their prices are a little higher. They generally don't try too hard to "push" chemicals but, on this item I am not so sure.

They want me to add some algicide (how do you spell that anyway :scratch: ?!) weekly. I didn't bother with the alg- my bleach keeping things largely in check. Also, I don't think I am using overmuch bleach either, about 4.5-5 gal.s/weekly on average. I added some algae control stuff two or three times as I deemed needful is all.
I also use 'pucks' to help hold chlorine levels constant. I use either with or w/out stabilizer depending on CYA levels. (I have and use my own test kit letting the pool store run their tests for a comparison. Our test results are generally comparable.)

Now, my wife is wondering if we used the alg-howeveryouspellit-cide, could we get by with less bleach? Is that the case and if so, is it desirable? Basically, we're wondering if adding alg-cide would reduce the chlorine/bleach requirement.

Other considerations that I can think of are cost? Is it less expensive just using bleach or would the mix (assuming it worked, is desirable) be cheaper?

What about chemical exposure? Is less bleach or alg-cide preferable as to what our hides are being exposed to? (Assuming chemicals in balance.)

That's about it.
Thanks for your replies.
 
Bleach will do the job period. Algacides sometimes contain things you don't want like metals. A pool properly maintained with bleach will never need algae killers. All the info you need to use it is right here at TFP. I applaud your support, but you can save some money if they carry an off brand. Provided it is just as fresh, it is absolutely as good as the name brand.
 
If you let the chlorine get low enough that the algaecide would be of any benefit, you are also letting the chlorine get low enough that dangerous pathogens can survive in the pool. Algaecide has no effect on those pathogens. Algaecide is essentially a masking agent for insufficient sanitatizer in the water.
 
Thanks! I was thinking along those lines but, just wanted to be sure.

My wife insists on the name brand, I could care less. There is one problem with some generics though. I have seen some that did not have any ingredients listing so who knows how much (or how little?!)% there might be. Those I won't touch.
 
If you wanted to use Polyquat 60 weekly and then target a lower chlorine level (FC/CYA ratio), that's up to you. We haven't determined the chlorine level needed to prevent algae growth when algaecide is used and yes, the rate of pathogen kill will be slower but in a residential pool that's not usually of great concern (bacteria are still killed much faster than they can reproduce). We don't recommend this combo approach because it's extra cost and more complicated, but it's your pool and if you absolutely want to use a lower FC level for your CYA level then an algaecide is the way to do that. Just know that your on your own, though you could report back with what you see -- at what FC level algae starts to grow (even nascent algae growth that results in higher chlorine demand even when the algae is not yet visible).

In my own pool 9-10 years ago when I was using Trichlor pucks, I also used a combo Polyquat/other algaecide though I only used it every other week. I started to get nascent algae growth when my CYA hit 150 ppm with an FC of around 3 ppm so had I used the algaecide weekly then perhaps the limit is 3 ppm with 200 ppm CYA or a 1.5% ratio. That was also when my phosphates were high so my best guess is that with algaecide you could have the chlorine be in the 2-3% range, say roughly half the recommended level in the Pool School, but that's really just a guess.
 
Having survived decades before CYA, meaning we got to zero FC every afternoon, I consider the pathogen thing pretty much theoretical for your basic residential pool, or, at least, my residential pool. (I know many on here disagree, but annual crypto cases from ALL sources comes to around 2 per 100k population/per year, including unchlorinated kiddie pools, community pools, and water parks.) That said, I tried the algaecide approach one year and did not continue. The only algaecide worth using that does not cause foam or have metals is the Polyquat 60, and it was at least $20 a quart at the time. For my pool, I needed essentially one quart for startup and five quarts for a season of maintenance, or $180 a season. At the time, that could buy you almost 50 gallons of 12.5% LC, or 223 ppm FC in a six-month season or almost 10 ppm FC/week in my pool. I could not save that much by running any lower FC I felt comfortable with at my usual 30-40 ppm CYA. It was pretty much a wash in dollar terms or a loss. So it became a trade-off whether I wanted more sodium hypochlorite in my pool or the nasty sounding stuff in the Polyquat 60. I went back to just LC.

P.S. Nobody got sick that year from my pool, either.
 
Just FYI, usually when one uses an algaecide to have a lower FC/CYA ratio, they don't actually lower the FC that much but instead get the CYA higher. That way, you lose even less chlorine from sunlight so can potentially save some on chlorine. The active chlorine level is lower so you notice chlorine's effects that much less. Again, not recommending this, just clarifying. The economics are still pretty much what you described -- you really don't save money with the approach and that's not the point of it. It's a cost vs. "benefit" where the benefit is having a lower active chlorine level (so less noticeable chlorine effects) if that's what one really wants.

At the time I was using Trichlor and algaecide, I was getting all my chemicals for free from a friend working in the industry so cost wasn't a concern. I also added metal sequestrant, clarifier and enzyme as well. And after a year and a half, I got algae growth and that's with a very low 0.7 ppm FC per day chlorine usage at the time (the pool wasn't used much except on weekends). Now I use only chlorinating liquid and a small amount of acid and the pool is used every day with around 1 ppm FC chlorine usage (we have a mostly opaque electric safety cover) and it costs around $17 or so monthly for the chemicals for a 16,000 gallon pool.
 
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