Another "Do I have Algae" question (sorry).


Well-known member
Jul 23, 2020
First - I've ordered my test kit but in the meantime, I went to the pool store and below are the results of my test:

PH - 7.7
Free Chlorine - 5.6
Total Chlorine - 5.6
Total Alkalinity - 84
Calcium Hardness - 156
CYA - 56
Optimizer - 4
Phosphate - 32
Salt - 3620

But my question is about algae. I've been working under the assumption I have yellow algae. The pool store wasn't sure, but told me to do a shock and put in a quart of algicide - which I did last week. It did not seem to work as I still had small patches showing up on the bottom of the pool. I'd vacuum them up or just brush them but they'd come back. Well, this morning I went out and nothing was there. Nothing at least that I can find. Is it possible that yellow algae would not be visible for a day or be sporadically visible?

A little more information. The patches appear in various areas. I've never seen it on the walls, just a few different areas on the floor of the pool. One pretty consistent patch (consistent in the area it showed up on) was on my tanning ledge. I scrubbed that really good (because it's obviously easiest to actually get to) and it has not appeared to come back. The patches do appear to brush away very easy. If vacuumed, they suck right up and if brushed, they just basically disappear with a little puff of "smoke" look. FWIW, the water is clear. I can see the bottom of the pool from inside my house. The pool is 6ft deep and the house window is about 15 feet away. Also, I noticed my wife lost a hair tie (small rubber band) by seeing it in the bottom of the pool. Subjective for sure, but it looks very clear to me.

I'm getting my FT100 kit (just ordered last night) and preparing to SLAM the pool, but I'm wondering if I actually have yellow algae. I was also wondering if I'm dealing with the remains of the algae after a successful shock. Though if it is yellow algae, I don't think I'm that lucky because I just did a normal shock with Cal Hypo. Nothing near the levels suggested for yellow algae.

Maybe I'm just impatient and I should wait for my kit, but I guess I'm hoping for a response like "yellow algae would show up every day". :)

Also, once I get my kit, I'm assuming the OCLT test will give a definitive answer. Is that true?


Gold Supporter
Silver Supporter
Jul 8, 2013
Columbus, Ohio
The OCLT will tell you what's going on. For now assume your CYA is 60 and keep your FC at the appropriate level for that. You min is 5 and you should be in the 7 - 9 range if your CYA is correct. Don't add anything that will raise your CYA in the meantime.


Gold Supporter
Bronze Supporter
Jun 11, 2018
Verona, MO
Be difficult to perform a proper OCLT without your own test kit. Margin of error probably too high.
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