Red spots in pool- pretty sure not algae

[delaneybob]

8,000 gallon Kidney shaped pool n ground pool- cartridge filter 1.5 Hp pump with additional Polaris pump

I maintain the pool myself and typically do stain removal in the fall. I keep PH at 7.2 and Chlorine between 1-3ppm.

Over the last couple months, I noticed algae building (I can remove that and have treated the pool with non copper base algaecide) and have CU-LATOR in the basket to help remove minerals. I have noticed red spots that appear as stains (see picture) that don't scrub off. The pool was installed in 2005 timeframe by a previous owner.

Pool pump runs 3-4 hours twice a day.

Wondering what the red spots are

Thanks

 

[Texas Splash]

Welcome to TFP! Without a few more answers and water testing, it's hard to tell. Here are somethings I would address first:
- Are you on a well? Wells = iron = staining.
- How are you testing the water? If not a TF-100 or Taylor K-2006C, that needs to be priority #1.
- How do you normally chlorinate? Please update your signature. See mine as an example.
- An FC of 1-3 ppm is almost certainly too low (algae). No algaecide or amount of filtering will kill algae. You need to follow the SLAM Process to completely kill algae.
- Try rubbing a Vitamin C tablet on those red spots (iron).

Let's start there and we'll see what we can do to help.

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[delaneybob]

Hi TFP
- Are you on a well? Wells = iron = staining. -
No not on a well- City water
- How are you testing the water? If not a TF-100 or Taylor K-2006C, that needs to be priority #1.
I use a T1000 and have a K2005 when need to test beyond CL and PH. These test are the same
- How do you normally chlorinate? Please update your signature. See mine as an example.
I use Liquid Bleach and Tti cholr floater/tablets
- An FC of 1-3 ppm is almost certainly too low (algae). No algaecide or amount of filtering will kill algae. You need to follow the SLAM Process to completely kill algae.
I am surprised- most sites say 2-4 (with kids) or 1-3 w/o kids. I shock every week with liquid bleach as well- I normally take it to 10ppm. What do you consider normal levels w/o kids?
- Try rubbing a Vitamin C tablet on those red spots (iron).
I will try that with the tablets I have

 

[Texas Splash]

I am surprised- most sites say 2-4 (with kids) or 1-3 w/o kids. I shock every week with liquid bleach as well- I normally take it to 10ppm. What do you consider normal levels w/o kids?

That's generic pool industry recommendations with no consideration for other factors. That's why we follow the FC/CYA Levels to keep the FC balanced to the current CYA. It's perfectly safe. The pool industry is finally starting to acknowledge this relationship and some companies are starting to change their recommendation. But accurate testing is a must.

Since you already have the K-2005, just order the FAS-DPD which essentially makes your kit a K-2006. Then you can be sure of accurate FC and CC testing.

 

[delaneybob]

CYA=60, FC=1ppm (this to expected as tomorrow I shock with liquid bleach ) Ph=7.2 the reason i have kept chlorine in the recommended low range is to avoid metal from staining the pool (the higher the chlorine- the more metals are dissipated form the water according to forums) . I have a CULATOR in the basket for this reason

on the red spots- the vitamin c rubbed it off but I also can rub it off with my finger- so it's algae

Looks like based on my calculator I need 36 oz of 7% sodium hypochlorite for every 3ppm for my pool- that would be 288oz of bleach (7%) to get 24ppm per the SLAM chart

 

[Texas Splash]

the reason i have kept chlorine in the recommended low range is to avoid metal from staining the pool

Understandable, yet now that you appear to rub-off the red with a finger, that rules out iron or copper, at least for those items specifically. Organic would go back to a SLAM Process using one of those test kits.

Now if you still have concerns about metals, remember that while you aren't on a well, some city water can have excessive iron. We might also need to consider copper. Have you ever used pool store copper products? Algaecides or pool products with the word Blue in them? Copper is a major pain.

But always remember that if a pool does get algae, a SLAM Process is first. "IF" there is a metal content in the water, it has to react and do its thing until after the SLAM is completed, then treat for the metals.

 

[delaneybob]

For the Algaecide- I always use In the Swim 60 plus- no copper.

Appreciate the help sir!

I will wait for the late afternoon and go scrubbing and then SLAM and will post back

 

[delaneybob]

Looks like the SLAM worked- thank you. FC is still coming down and will keep the pol around 5ppm FC going forward base don my CYA of 60

 

[Newdude]

Follow the FC/CYA Levels religiously. It is the holy grail of TFPC.

if you do, there is zero need for algecide. If you don’t there is need for another SLAM and still zero need for the algecide. $4 a gallon for bleach whoops $28 a quart of algecide on every level.

Also, belated Welcome !!