Combined chlorine after quat algaecide

Infamy1406

Member
Dec 12, 2021
8
Adelaide
Pool Size
32000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Astral Viron eQuilibrium EQ18
Hi all

New pool owner.

Been dealing with a persistent mustard algae issue and mistakenly followed advice from pool shop on how to treat it.

I had brought my pool to shock levels consistent with guidelines here (but not quite to mustard shock levels) - I hadn’t seen this at the time.

I seemed to have the algae at bay with just some minor spot re-occurrence in the same locations. On advice of the pool shop I decided to try and completely eradicate with the use of a quat/copper algaecide (50g/L organo copper complex + 100g/L benzalkonium chloride ammonium quaternary).

I ran my SWG at 100% for the following two days and my pool shop results were

10 FC
0.9 CC
80 TA
7.5 pH
CH 220
Salt 3500
CYA 27

This is the first time I have seen a CC reading since owning.

Reading up on the action of ammonia based algaecides - they react with free chlorine to form chloroamines.
From what I have read from other similar algaecides - this affect is temporary but I have been 3 days since the treatment?

Should I continue to wait or do I treat this ASAP?

My understanding is preferred option is super chlorination to break point is one option or non chlorine based shock (Potassium peroxymonosulfate).

I ask because I either let my FC drop by stopping SWG for a day or so - or superchlorinate now as it will only be a relatively minor FC increase?


Noting - the CC to FC is already above the 10x ratio I have read about?? Which makes me wonder if this is indeed ‘temporary’?

Thanks in advance!
 

Infamy1406

Member
Dec 12, 2021
8
Adelaide
Pool Size
32000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Astral Viron eQuilibrium EQ18
Update - Had my water tested again today - note I can't buy a decent home test kit like a Taylor in Australia - and I am waiting for several weeks for shipment from US.
All test kits available in Australia look like a basic/generic kit. Is this going to better than a pool shop test still though>>

FC - 7.44 (decrease as I reduced SWG output slightly yesterday).
CC - 1.61 (increase)

All other variables were quite similar.

So the CC has further increased. Weather has been warm and sunny over the weekend gone.

Following the SLAM method is going to be difficult without a decent home test kit and I need to rely on store tests in the short term

Should I be concerned about the CC level (and the increase)? My feeling is the use of the algaecide is the cause of the CC. My reading suggessts Algae treatments can increase CC readings, but it doesn't go into further detail around this?

Do I wait this out or take corrective action on the CC?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,341
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I believe that is what we call polyquat. If so, it does not effect CC.
Algaecide is completely unnecessary. Use Chlorine.
 
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