how often to apply polyquat

[maxhiller]

first my numbers:
CYA: 50
pH: 7.5
Alk: 90
Cal: 100
I use BBB, keeping my FC between 3-5 (i "top off" the FC to at least 4.5 every night)

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i had a small growth of green algae, so i've shocked.

i want to add polyquat as a 2nd level of defense. i've purchased bioguard's 60%.
their label states
1) 6-11 oz/10000gallons for initial dose in freshly cleaned pool
2) then 2-4 oz/10000 gallons every 5-7 days

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Finally my question:
Do i really need to keep adding it every week ? (the polyquat breaks down that fast ?)




Thanks in advance
max

[chem geek]

The PolyQuat 60 doesn't get broken down very quickly -- it's a pretty stable molecule. High chlorine levels will cleave the polymer into smaller pieces (and hence use up chlorine doing so), but these smaller pieces are still effective. It eventually does break down, but mostly what happens is that it acts as a clarifier and binds to algae and particulate matter and then gets caught in your filter. Also, some gets diluted from splash-out or backwash, just like everything else in the pool. The chlorine does break it apart slowly eventually.

The manufacturer's recommendations for a maintenance dose are generous (and more profitable). You can most likely get away with half their recommended amount -- say, 1 ounce per 10,000 gallons. I believe Carl uses such a relatively small amount in his pool. To be effective, however, you do need the initial dose amount on first addition or at least build up to that amount. Taylor sells an expensive test here that will measure PolyQuat (and linear quats, QAC, as well, but you're not using that).

Richard

[maxhiller]

thanks !
max