Might have mustard algae

[ping]

Hi everyone, my first time posting but have been reading on this site since my pool was built in November, 2010. We live in Long Beach, CA.

My numbers first:
FC 24
CC 0
pH Lowered to 7.4 at start of shocking was 7.6
TA 90
CH 230
CYA 80
Salt 3400
Borates 50
Temp 80-85 was running 86-90 with cover before shocking

Now on to my problem. I have been having a hard time keeping up with the min FC level with a 13 hour run time and 100% output on my SWG. I have been keeping up by adding bleach for the last 2 months. My CYA level was low, 40, so I started to increase this to 80. I have raised the CYA to 80 over the last 3 weeks and the SWG still can not keep up. The wife has been teaching lessons so I did not want to shock the pool, and we now have a break so I have started the shock process 2 days ago. The water has always been crystal clear, CC's usually have been .2-.5 but are at 0 right now. We are losing about 5ppm FC each night at these shock levels, but only about 1.5ppm when we have a normal 5ppm FC level. My question is, should I be targeting mustard algae levels or just standard shock levels? I have noticed some yellow stains mostly on the deck and coping areas appearing this last week. There is one yellow stain in the pool next to a return. The stains are about 2" X 3" in size. The pool and deck are in full sun all day long. I tried brushing and scraping the stains with my nail, but the stains did absolutely nothing. Yesterday I sprayed a 50/50 bleach water mix on the stains and they went away. The stain in the pool has lightened up considerably. I have never added anything with metals in the water and we have good fill water. I did add borates to the pool 2 weeks ago using 20 Mule Team and MA. MA and bleach are the only other chemicals we have added to the water since we filled the pool. I will continue shocking until I reach <1ppm loss over night.

Thanks for all the help,
Paul

 

[JasonLion]

Remember to brush the entire pool daily while shocking. You should also look around for places algae might be hiding out, undersides of ladder steps or underwater light niches, or other nooks and cranies and make sure those places are algae free.

 

[Butterfly]

Hi Paul

Since you have a plaster pool, I suggest a more aggressive shock process.
The CYA/Chlorine chart in Pool School has a higher shock level of about 31 for your 80 CYA.
The Pool Calculator is less aggressive with shock level of about 21.
I'd turn off the SWG and use liquid chlorine/bleach and shock at a higher level tonight.

Also, if you feel convinced it is mustard algae, shock to mustard algae levels and toss into the pool any toys, tools - everything that has touched the water like poles, nets, brushes, etc.

Wash all swimsuits in soap and water.
All those kids that DW was teaching need to have their swimsuits washed, too.

If it is mustard algae, it can easily be reintroduced into your pool.

 

[ping]

Hi Paul

Since you have a plaster pool, I suggest a more aggressive shock process.
The CYA/Chlorine chart in Pool School has a higher shock level of about 31 for your 80 CYA.
The Pool Calculator is less aggressive with shock level of about 21.
I'd turn off the SWG and use liquid chlorine/bleach and shock at a higher level tonight.

Also, if you feel convinced it is mustard algae, shock to mustard algae levels and toss into the pool any toys, tools - everything that has touched the water like poles, nets, brushes, etc.

Wash all swimsuits in soap and water.
All those kids that DW was teaching need to have their swimsuits washed, too.

If it is mustard algae, it can easily be reintroduced into your pool.

Thanks for the tips. I tossed everything in the pool yesterday.

How long should it soak for?

Should I remove the lights from the niches and scrub them or just brush extra near the lights?

When I run the calculator it shows that I need a level of 44 to target mustard algae with a CYA of 80.

I do have the SWG turned off and I'm just adding 182oz. bottles of Clorox. Another trip to costco is schedule for me on my way home from work today.

Thank you,
Paul

 

[Butterfly]

How long should it soak for?
Don't know that I have heard an exact amount of time, but I could guess.
Perhaps a few hours would do, but we'll wait for someone who knows to answer this for you.

Should I remove the lights from the niches and scrub them or just brush extra near the lights?
Removing the lights from the niches and scrubbing them could only help, esp since you are going after mustard algae.

When I run the calculator it shows that I need a level of 44 to target mustard algae with a CYA of 80.
Yep

I do have the SWG turned off and I'm just adding 182oz. bottles of Clorox. Another trip to costco is schedule for me on my way home from work today.
You'll get it done! Keep us posted.

Thank you,
You're welcome!
Paul

 

[ping]

I have finished shocking the pool and passed the OCLT!

The process took about 5 days to pass the OCLT with the first 2 nights losing about 5ppm per night. My last test I only lost .5ppm, water is sparkly clear, and CC=0.

I figured out what my yellow stains were, and are now there again, the boys have, "had", 2 old waterpolo balls and they were leaving marks on the decking and coping when the ball was thrown hard against the surfaces. Bleach removed the stains but scrubbing didn't, strange.

The SWG is set to 20% and the Cl level is increasing. I just asked the wife to turn it back to 0 so the Cl drops. It has been about 2 months since that has happened even with 100% output.

I have some questions about my cover since it was in the pool with all the algae. We are finished with the cover for the summer and I'm wondering what I need to do to store it? I store it in my garage but I'm wondering if the algae will survive and be reintroduced to the pool in the fall?

Thanks,
Paul

 

[RobbieH]

I was going to say, mustard algae will make a yellow plume when you brush it.

 

[captjohn]

I've had a similar problem with high chlorine usage but had sparkling water. I looked at my pool light since I've occasionally seen sediment come from that area when brushing. I prepared myself with my vacuum hose in 1 hand, screw driver in the other and my wife at the pump/filter control. Vacuuming to waste, I removed the light to find unbelievable, nasty, black, slimy (getting the picture?) stuff, I'm guessing algae. Chem Geek suspects black or heavy yellow mustard. I got 90% of it out to waste but the rest got in the pool. I had to go to filter since I was almost below the skimmer and picked up 90% of that. I backwashed a couple of times until the water was low again. I've raised the FC to 24 (actually landed closer to 30), Mustard Algae level for CYA of 40, and removed the light and all wire and it's in a bucket of 10% bleach/90% water. I think I'll change that water in about an hour and retreat over night, if not all day tomorrow too! I'll throw all the brushes, toys, etc. into the pool tomorrow.
OK, now to how it got in there. I wouldn't think it would occur in a balanced pool, would it?? Although reading this thread, I guess it can, BUT.......
6 years ago I was flooded by Hurricane Katrina and my pool was 12' under water. After cleaning potted plants, mud, furniture, shrimp, fish, crabs and salt water from the pool, the water cleared up enough for me to remove the light, clean all the jets, filter, etc... Thinking back, I don't think I cleaned the conduit to the light. The wire was also black and slimy as I pulled it out. I've poured aprox. 96 oz. if bleach into it and plan to pull a rag through it and treat again.
Hopefully, I've found the cause and can cure it. If you have any suggestions for me, I'm all ears.
Ping, I hope you have yours under control also but consider checking the light.