New AG pool owner: Gray spots, gritty sandy stuff in sock?

[Nadrek]

We bought the house late last year, and it came with the pool, including clear water and a K-2005 kit. After closing last year with shock and Polyquat, we opened this year to clear water, some gray spots on the bottom, two small sets of black spots on the bottom, and an order for a K-2006 kit (which has since arrived). Due to trees, we're getting a very few leaves, a lot of small flowers, and a lot of helicopters in the pool (or on the solar cover, whichever is exposed).

I do not know the age of any of the equipment.

With the eyeball pointed sharply to the right (away from the skimmer entrace; the eyeball is a few feet to the right of the skimmer), a strong counterclockwise water rotation forms when the pump is on.

Given the gray spots, with the K-2005 I brought the pool up to approximate shock and kept it there, and vacuumed the gray spots up regularly; I was hoping they'd quit forming. This has not happened.

Current status, per K-2006:
FC 25.5 (at 0.5 accuracy)
CC <=.5 (at 0.5 accuracy)
pH 7.8 (false reading from high FC)
TA 90
CH 160
CyA 60
Water temperature 67
Automatic feeder set at 0.5 until it runs out (I just want to run it dry, rather than deal with the pucks)
DE filter PSI 17 (it opened at 16 with fresh DE).
Locally heavy rainfall raised the water just above the skimmer basket yesterday, I pumped out 1.5" of water, and the really nasty surface Crud is gone again.

My questions:
A) Can I actually use the overnight FC loss method when new Crud is constantly landing in the pool?

B) What are those #$%#$ gray spots on the bottom; they accumulate in the same location most of the time, and along the creases in the bottom of the vinyl liner (there are 3 such parallel creases). I've brush/vacuumed those from multiple angles repeatedly. The grey spots keep coming back.

C) Upon putting a skimmer sock in the skimmer, it quickly gets coated with a slightly gritty, sandy substance, whether I've vacuumed or not. What is that? I did notice that when the pool water was above the skimmer, in addition to a couple leaves and a lot of helicopters and small flowers, there was a good speckling of small particles on the surface.

C1) Is the skimmer sock picking up that substance good for my DE filter in general?

D) A flashlight underwater at night showed that the bottom of the pool is most definitely not smoothly even, particularly where the grey spots show up. Is the flat blue plastic vacuum head I have the best choice to clean up stuff that may be in the depressions?

 

[Bama Rambler]

A) Yes you can perform the overnight loss test. If you think about there's never a time in an outdoor pool that there's not something falling into it.

B) When you vacuum the floor do the gray spots suck right up into the vacuum? If they do it could be dirt or dead algae.

C) The skimmer sock is doing exactly as it's designed to. Picking up stuff whether vacuuming or not is a good thing.

D) Dirt and dead algae is bad about settling in creases and dimples. Since you say the skimmer sock is picking up stuff whenever the pump is running I think that's what it is.

 

[Nadrek]

B) When you vacuum the floor do the gray spots suck right up into the vacuum? If they do it could be dirt or dead algae.

Thank you for the quick reply.

Yes, the gray spots are always vacuumed up without incident.

 

[Bama Rambler]

It sounds like your filter just needs time to filter everything out. How many hours a day are you running the pump? Keep an eye on your filter pressure and backwash as needed. Be sure to replentish it with the proper amount of DE after each backwash.

Do an overnight chlorine loss test and let us know the outcome. If that passes let your FC drop back to normal levels for your CYA and run your filter 24 hrs a day till it clears up.

 

[Nadrek]

Overnight chlorine was from 19.5 to 22.0 (the auto-feeder was still on 0.5!); I probably can't get a reliable test until it's empty.

Pump is 3x4hrs a day.

 

[Bama Rambler]

I probably can't get a reliable test until it's empty.

That's right! Or at least set to zero. Sorry I didn't mention that sooner.

I'd run the pump 24 hours a day until you get this cleared up. You can run it on the schedule, just realize that it's going to take much longer to clear it up.

 

[Nadrek]

It's a mechanical timer, black knobs for off and silver for on. How do I set it to run 24/7?

 

[Bama Rambler]

There shoudl be a manual switch on it but if not post a model number of the timer and we can walk you through it.

 

[Nadrek]

My apologies, it's actually a Paragon 4001-00. There is a mechanical on/off switch I've used quite a bit, but it only overrides the current timer section, as the automatic on/off actually physically moves that very same switch.

 

[Bama Rambler]

According to the manual you just flip the manual switch to on to keep the load on all the time.

 

[Nadrek]

Thank you; I'm not sure that's quite the way it works, but for now things appear under control.

I think I'm going to pick up a 10cc syringe to measure the water for FAS-DPD; I did the overnight test, and the FC reading at night was the same as the one in the morning (17) without any CC. Unfortunately, I did 3 FAS-DPD FC readings out of the same sample bottle, and got a ~1.5PPM variance, so I'm really not confident in it. I was trying the 10ml sample, 0.5ppm accuracy.

 

[Bama Rambler]

You'll get better the more you do it. I use a 10ml syringe to dispense the sample into the vial too. To me it's a little more repeatable than trying to figure out where the meniscus line is on the vial.

The way I do the FAS-DPD test is to first rinse the vial with water from the pool and then add 10ml of it to the vial and start the stirrer (I highly recommend you get one of you don't have one) and let it stir as I put 1 heaping scoop of powder in the vial. I then open the reagent and start dropping drops into the stirrer. I count each drop until the water turns completely clear and the last drop doesn't make a change then I subtract the last drop from the total and multiply the result by .5 to get my reading. I said all that to get to the point about the last drop because there's a difference between clear and almost clear. If you make an extra drop that doesn't change the color any more then you know you've reached the end point. All you have to do is not count that last drop. I find that doing it this way provides more consistant results.