Red Algae on Steps

[Skimis]

I've been using the TFP system since the middle of last year when I switched from Dichlor tablets to a SWG. My water has been perfect, and was near perfect on opening 6 weeks ago. About 2 weeks ago I noticed some red stuff on the steps and in my cove - both white plastic areas with rough surfaces. First I brushed it off and added a dose of algaecide. It was gone for a few days and yesterday I noticed it again - it doesn't seem to be the slimy (comes off in sheets) stuff. Looking for some input before I resort to SLAMing the pool. My pool info and TFP test results as of this evening are listed below. Thanks for any ideas.

- Location = southern NJ
- 21,000 gallon vinyl liner in-ground pool
- SWG running 65% (increased to 80% this evening and letting it run overnight)
- Hayward pro-grid DT filter
- Pump runs 6 hours / day

FC=2.5 (typically this runs 3.5-4.0; 6 days ago it was 3.5)
CC=0.5 (I almost always get a little pink when I add the drops again)
PH=7.4
TA=100
CH=80
CYA=40 (50 24 days ago, 40 last week)
Salt=3000
Temp=87

 

[duraleigh]

Red? Can you get a picture?

 

[Skimis]

It's dusk so not a great photo, but you can see it here. It's all over the cove and steps except for white streaks where my wife swiped it today.
Had a hard time uploading an image.... Insert from Computer doesn't provide a way to point to the file, used URL and it kept complaining the file is too large (32k), so I tried just using the link.
Here's the link to two photos - I'll get better pics tomorrow morning
https://www.dropbox.com/s/k4dlfa3fc1y89vb/RedStuff3.JPG?dl=0
https://www.dropbox.com/s/qjzak0oopkrkw87/RedStuff2.JPG?dl=0

 

[Richard320]

That is pink. Maybe you've got Ketchup Algae!

Sorry, I have nothing constructive for you. I have no idea if a SLAM will kill it, or if it's some kind of mold like the bacquagoo people get, or what.

 

[domct203]

Can the pool pass an Overnight Chlorine Loss Test?

 

[Skimis]

I think so... but I'll confirm in the morning...

 

[JoyfulNoise]

You should do an overnight chlorine loss test. If you raise your FC to 5ppm with liquid chlorine and get an accurate measure of the FC after sunset, then your OCLT should be less than 1ppm when you measure again in the morning. If it's more than 1ppm loss, then you need to SLAM. Trying to identify something by it's color is not really going to get very far...red algae is highly unusual to get. Simply do the OCLT and proceed from there; if it is biological in nature, the SLAM will kill it no matter what color it is....

- - - Updated - - -

and make sure the SWG is not running during the OCLT

 

[wjr75]

I get a red film on my slide steps which catch a little rain water. I have two huge white pines and a couple of other tree's and suspect it to be some sort of pollen from the tree's. Never have seen it gather in the pool but I have an auto cover which is closed most of the time when the pool isn't in use.

 

[PoolguyinCT]

Is this the shady side of the pool? It looks like a fungus, so oclt may not be a great indicator.

Chlorine will kill it, & regular brushing with mindful water management will keep it away.

 

[Skimis]

Thanks for the suggestions. I checked this 'red' stuff this morning, and it's not red algae - it's actually pink and dissolves in a cloud when disturbed. My FC last evening was between 2.0 and 2.5. This morning it is 1.5 - not a horrible drop, but far too low and there is some growth in the pool. I think I've let the FC level run too low and probably my CYA is low for this SWG pool. So I'm going to SLAM it and then run up the CYA to 60.