High CYA: Draining advice

[crumley]

Hi All,

Been having trouble with my puck fed pool and algae blooms. Algae was growing on floor particularly around edges. Shocked and shocked and couldnt get pool to stay clean. Brushing bottom would bring up grey looking dust. Went to pool store and tried some bromine but a week later and the algae is back. Finally got a Taylor K2600 test kit and giving up on the pool store. As you might expect my CYA is off the charts. Here are the measurements:

FC: 4
CC: 5
CYA: ~ 450!

From pool store measurements:
PH: 7.2
Hardness: 500
Alkalinity: 90

I'd like to get this under control and with such high CYA and Hardness it appears draining and BBB appears to be the right option. Agree?

I live in a protected water shed and can't drain to the storm sewer unless the chlorine residue is less than 0.01 mg/L. Also would need to figure out to limit the flow.

I have some vegetated areas in my yard but not sure they are large enough to handle 10k gallons without bad effects (hurting trees / bushes / etc ).

Any draining advice? Am I better off getting the FC down and risk the pool getting greener then drain? How about draining 2k per day?

 

[jblizzle]

Well, You are going to need to replace 90% of the water. What is the groundwater level by your pool? You may not be able to drain it all at once if you have high groundwater.

If you can do it all in one go, then I see no point in trying to maintain it clear ... and you can let the FC drop.

You have competeing goals which you can not do both. You either have to maintain VERY high FC to keep the pool somewhat clear OR let the FC drop so that you are allowed to drain it.

 

[crumley]

Unless I hear otherwise from the excellent people on this forum I would like to drain (and not do something stupid in the process =) ).

If I can't do it all in one go, should I try to maintain the water clear? Is that going to be possible once the pool is near empty?

I will see if I can find out the groundwater level. I live in central Texas where there is a ton of limestone.

 

[zea3]

You can drain down til there is about a foot left in the shallow end, then refill. After refilling run the pump for about an hour then test the CYA. If it is still too high you do the drain/refill cycle again. I wouldn't bother trying to keep it clear while you are draining and refilling. It won't make clearing the pool any quicker and the algae won't hurt the yard. Set up the pump so it draws out of the deep end and brush the pool well so the debris settles near the pump intake.

 

[crumley]

Drain is in progress. Started with the filter set to waste and a backwash hose but it was making a big mess. I am using a hose hooked up to the spigot on the pump and moving the hose around the yard. Much slower but is controllable. Pool level is just starting to get under the return jets.

I turned off my skimmers and only have the main drain open. I have a spa which is slightly higher than the pool and spills over. Should I worry about draining it or just focus on the pool?

Also noticed I have what looks like a drain on a vertical wall in the deep end just under a return jet. Any idea what this is for?

 

[jblizzle]

Does it look like a drain or just a deep return jet? Any chance there used to be another water feature pump or something? I had a hole under our waterfall and eventually discovered is was capped off near the equipment ... I have since plumbed it back in to be a second suction line for my filter pump.

 

[crumley]

It looks exactly like the two drains on the floor of the deep end. I do have a second pump for a water feature. Makes sense it would be for that now that you mention it.