How to clear water / valve problem?

[dmdrums]

Hello-

I have a 15K gallon pool that I made 2 mistakes with.....

1. Let CYA creep to 140 with tri-chlor tabs
2. Let FC fall to 0 for 5 days in Arizona at 95 degree outside temp
Pool had algae on the PebbleTec, but was otherwise clear. After brushing, looked a mess.

The fix:
Drained approx. 75% of the water

CYA went from 140 to 75. I can't explain this one....but was hoping to at least use tabs during vacations. At CYA 75, I don't think I can at all now unless I drain MORE....bummer!

Shocked pool with liquid chlorine at dusk - used 2 gallons (getting smarter...put away my 30 pounds of powder shock). FC tested to 20 the following evening. FC remains over 5 after 3 days, so I have yet to add more.
I have now run the pump on low speed (approx. 25 GPM) for 16 hours per day for 3 days.

Ph is down to 7.5 (was over 8 before I shocked....I'm aware FC over 10 changes Ph so I tested BEFORE I shocked and not again until today).

I am backwashing evey evening and brush entire pool every evening.

However, I STILL have clouds (getting smaller) of algae when I brush.

Here is what seems strange and I need some help to know if these things are causing me problems.......

1. I noticed while backwashing that approx. 1 minute into the backwash, I can see some (not a lot) dirty water coming out of the jets in the pool.
2. I think the spider gasket still leaks slightly, which is why I have a 1/4 turn shutoff on my backwash line (I am great at remembering to open this when backwashing and closing afterward). I just replaced the spider gasket last year (made a huge improvement at that time, but it never 100% fixed my "leak".
3. I have a Purex Triton sand filter but I don't know the age of it or the sand in it. 7-way valve and filter looks faded and 7-way is losing the sticker that says position indicator. Filter currently needs replacement gasket on top of tank, as it leaks very slowly (on my someday list). Pressure gauge cracked last year, so I replaced it (was squirting from the side). Hope this reveals the age of it.

This being said, what do you guys think?

It is time to replace the filter, the sand, 7-way valve? Used the ZeoSand at my last pool and I was quite happy with it (random thought). Do I fix these items or replace them?

Also, do you think if the 7-way is "leaking" to other positions, would this make the pool murky? I know it tends to "leak" very slightly to backwash and now I blocked that from coming out.....maybe all this goes into the pool now?

The pool isn't bad per se, it just seems to be taking FOREVER to clear up.

I attached a photo so you can see. Looks a bit worse from the camera phone photo than it really is. This photo was taken tonight right AFTER I brushed the pool to stir everything up, so this is the worst case scenario.

You can easily see the Polaris and the main drain, granted the pool is only 5' deep.

Thanks for your advice!

Dmdrums

 

[JohnT]

I'd say it's a good shot that your multiport gasket is in need of replacement.

The CYA test isn't really accurate at low levels, and it goes to heck at higher levels, so your reading of 140ppm could easily have been much, much higher.

You want to keep the chlorine at a higher level until the water is clear. TheChlorine CYA Chart will give you a guideline as to where to go. 5ppm is really below the lowest you should ever let it go with CYA at 75ppm.

 

[madwil]

Sand doesn't need replaced, but the valve may if replacing gasket didn't fix your leaks/crossover between settings
The slight crossover isn't the end of the world, but does decrease your filter efficiency- hence taking longer to clear up.
John is right, you need to maintain shock levels of Cl until the algae is cleaned up- your algae is growing almost as fast as dying at your current level, also increasing clearing time!