Shock And Poly60

[muss51]

Does shocking a pool have any affect on poly60 algaecide or vice versa? Can you add the two at the same time?

[chem geek]

Does shocking a pool have any affect on poly60 algaecide or vice versa? Can you add the two at the same time?

Chlorine does (normally slowly) break down PolyQuat 60 into smaller units so if you shock with chlorine when PolyQuat 60 is already present or if you add PolyQuat 60 to a pool with high (FC/CYA ratio > 0.2) levels of chlorine, then you may find an unusual chlorine consumption. This thread at The Pool Forum goes into detail of what happens, including a response from Buckman Labs who make PolyQuat 60. They basically say that even though PolyQuat is split into smaller (even monomer) subunits, that it is still effective in inhibiting algae growth. So the only real side effect is extra chlorine consumption. At normal chlorine levels, this consumption rate is low though this is part of the reason PolyQuat needs to be added weekly (the other reason is that it is also a clarifier so will get caught into the filter and likely backwashed away).

PolyQuat is effective at inhibiting algae up to a certain point, but it generally gets overwhelmed during an algae bloom (because PolyQuat is slow-acting). So it is best used as a preventative (mostly as insurance, since chlorine alone can keep away algae) and not for fighting an existing algae outbreak. Shocking with chlorine (at FC/CYA ratio of 0.4) is effective at killing green algae relatively quickly. Use of a copper algaecide is also very effective, but has possible side effects from the copper (staining plaster surfaces at higher pH and blond hair getting a greenish tint).

Richard