Is Algae Possible? CC=0

I have a 23 yr old concrete pool. The floors are white and have not been resurfaced. All the surfaces SEEM to be in good shape in terms of smoothness. I have only owned the pool/house for a month and a half so I can't remember what the floors looked like before I bought the house and was taking care of the pool.

With the information this forum provides, I did my homework and have kept my water clear so far. The white floors seem to be tinted a slight green. The floors are not covered by the green, rather it is sporadic and mostly in the shallow section. Any idea what is causing the discoloration?

As of this morning:

FC: 8.5ppm
CC: 0ppm
CYA: 70pm
pH: 7.4

Is the presence of algae possible when CC=0?

I will take pictures later this evening as the discoloration is easier to see without direct sunlight.

CC levels have no direct correlation with algae. One form of combined chlorine -- monochloramine -- is a VERY effective algaecide and is used for that purpose. Other chloramines are weak algaecides; others have little effect, and for many, the effect is not known.

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Originally Posted by Shifty

Is the presence of algae possible when CC=0?

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Yup, I've seen pools with full-blown algae blooms (including my own) with CC=0.

Janet

Is it possible to have algae but your water is clear?

It's possible, but it won't be clear for long. Check your chlorine level at nght and again the next morning before the sun hits the pool. If you lose more than 1 ppm in that time, then something is eating your chlorine. If you don't lose chlorine in that time, you don't have algae.

I defintiely don't have algae then. The discoloration has been on the floor since I noticed it over a month ago. My water has been clear the entire time. Any other thoughts? Metal? I tested my fill water, but not for metal.

The quick test for iron stains is a handful of Vitamin C tabs on a stained area for a few minutes. If the Vit. C lifts the stains, it's metal, probably iron.

I have yet to try the vitamin C tabs on a stain; however, I was able to get my hands on the most recent water quality report for Philadelphia, PA.

Cl= 1.9-3.1 ppm
pH= 7.4 ppm
TA= 60 ppm
TH= 135 ppm
Lead= 90% of the water tested had less than 5.8 ppb
Copper= 90% of the water tested had less than .32 ppm

With those traces of lead and copper, is it possible to produce stains?

0.32 ppm of copper could stain; the lead will not.