Pink slime!

[waterbear]

Bottom line is this, if you got pink slime your chlorine was NOT high enough. To kill it shock the pool to the shock+ range in the best guess chart.

When shocking it is better to add bleach or liquid chlorine instead of the boost function. One main reasons is that you want the high FC level immediately and not over the course of 24-48 hours. A second one is the boost function does shorten cell life.


As far as the CYA goes, higher CYA indirectly leads to better pH stability because it directly translates into less cell on time which translates into less formation of hydrogen bubbles which translates into less aeration of the water which translates into less outgassing of CO2 (which is the main cause of pH rise in a salt pool), which translates into slower pH rise.
On the same note, the lower you put the pH the faster it will rise so you will get better pH stability for a longer period if you do not lower the pH below about 7.6 and only add acid when it rises above 7.8. (easy to do using your test kit's acid demand test).

Your waterfall is a source of aeration also and is contributing to pH rise so you mgiht benefit by lowering the TA to about 70 ppm or even 60 ppm and raising the CH to still keep the water balanced. (around 450 ppm will keep your water balance at a pH range of 7.6 to 8.0).

Finally, you might want to consider adding borate to 50 ppm for it's many benefits, including better pH stability and it's algaestatic action.


Your CYA should be around 75 or even 80, particularly since you are located in Florida (so am I) and you should run the FC at 4-5 ppm. You should not need to be adding polyquat at all with a SWCG that is operating properlysince chlorine levels will stay pretty constant. Also, polyquat does cause a temporary lowering of the FC in the pool.

(Carl, while it is true that higher pH does make chlorine less active IN AN UNSTABILIZED POOL it changes once CYA is added to the mix and the effect of pH on a stabilized pool, while still present, is minimal.)

As far as the grout problems, it is definitely a water balance issue. Your calcium is way too low and most likely, when you added acid to drop the pH (which you said often went down to 7.2 or 7.4), your calcium saturation index dropped low enough on the negative side to make the water aggressive to plaster and grout. For example, given the water parameters you listed and a temperature of 80 degrees for the water ( not uncommon in Florida) your CSI would be about -.7 which is definitely aggressive!