First test - CYA 285 and next steps

[milesandmiles]

I just took my pool over from a weekly pool service and did some tests with my new K2006 kit with Fas/DPD.

FC: 16.5
CC: 3
Ph: 7.2
TA: 100
CH: 500
CYA: 285 (had to dilute the sample 2:1)

I’m thinking about the following as next steps:
1. Stop the use of chlorine tabs
2. Start pumping water out and replacing it. We are on water restrictions (Austin). I’m thinking I could do this gradually over 90 days. I don’t have a good place to dump 10,000 gallons of hyperchlorinated water.
3. Look into SWG.

Does this sound right?

I’m wondering how high I need to maintain FC in the interim, given the CYA is so high.

 

[dfwnoob]

That is such a ridiculously high, completely over the top level of CYA that the only real option is to refill. You will never be able to maintain the FC to a level that would keep it safe enough to swim.

I would look into a water trucking service to get around your water restrictions.

 

[ajw22]

Pumping water out a bit at a time will be the proverbial drop in a bucket and waste a lot of water in the process due to continuous dilution.

You need to replace 75% of your water to be down around a SWG CYA level of 70.

Use a water truck service to fill your pool. I filled my pool with four 7000 gallon truckloads of water.

 

[milesandmiles]

OK, so a drain+refill in my future, and that will give me a chance to do some tile repair, too.

 

[an1vrsy]

Does your residence have plumbing cleanouts, around the perimeter foundation? Austin isn’t Las Vegas, we are in water restrictions. Here, to drain a pool, you must pump to the cleanouts. Water running down the street will get a resident a huge water waste fine.

 

[mgtfp]

I’m wondering how high I need to maintain FC in the interim, given the CYA is so high.

The target FC in the FC/CYA chart is about 12% of the CYA. Let's call your CYA 300ppm, that would make a target FC of 36ppm. The min FC in the chart is about 8% of the CYA, that gives you a min FC of 24ppm.

You don't want to do that. Your best option is to drain and refill asap.

 

[mgtfp]

If water restrictions are an issue you can try to find a Reverse Osmosis service:

Reverse Osmosis - Further Reading

www.troublefreepool.com

 

[milesandmiles]

It looks like the city will allow the water into the storm drain if chlorine is less than 1ppm. It will take about two days to fill the pool from the hose, but this should be cheaper and more feasible than getting trucks in, or RO.

There is a silt or something in the pool. I've wondered if it is non-green algae of some sort. In full sun the pool looks crystal clear, but when I brush it's like I'm dusting the pool -- the steps, the walls, the floor all seem to have a dust on them. Could there be so much CYA that there are solid deposits? Dirt? Algae? I can do OCLT, and I guess it doesn't mater if I'm doing a drain/refill, but I'm curious.

How long is it "safe" to leave the pool empty? We are on a hill and on limestone, so I don't expect there will be a high water table to "float" the pool. It could be very hot, though.

I really appreciate the help here.

 

[mknauss]

You do not want plaster to dry out in hot sun. A no drain exchange is safer.
See the Draining wiki.

 

[milesandmiles]

You do not want plaster to dry out in hot sun. A no drain exchange is safer.
See the Draining wiki.

I can see how this could be stressful for the plaster, and me

OK, checking out the RO option. Saw one service that will leave a trailer in the driveway for two days and just take care of it. Will report back.

 

[milesandmiles]

I ran the CYA test again today, in brighter sun, and I got 160. Took sample to pool store and they said 185. So I think the 285 was in error. Based on this, I think a series of drain/exchange/fills could work. RO treatment looks like it will run north of $700, so I thought I would try.

I got a $80 submersible pump that dumped a whomping 30gpm through a backwash hose. Switched pool pump off at the breaker box just in case. Started at 6pm to avoid exposing pebble to the worst sun. The pool was already quite low (evaporation). Pump ran 2 hours or about 3,600 gallons.

I went ahead and put the full hose in the deep end when I started. It’s running about 6gph, so it’s not really an exchange but sort of. This makes it easy to spray the exposed pebble every 30 minutes or so.

If my math is about right, pool should be filled around sunrise. Then I’ll run the pump a bit (not sure how long?) then take readings.

I should have arranged to smoke a brisket overnight while babysitting the fill hose.

As I put the fill hose in, I realized the pool is going to cool down a bit, which is very welcome this time of year. My first pool robot arrives tomorrow via recommendations here (Dolphin Active 20 from Marina Pool Supply). Hoping to be in a better place with the pool this weekend.

Really appreciate the help. This place is awesome.

 

[mknauss]

I assume you ran through the calculation on determining where you are to pull water from and add water in the pool to exchange.

 

[milesandmiles]

I assume you ran through the calculation on determining where you are to pull water from and add water in the pool to exchange.

I did not - could have planned that part better. I was thinking the temperature delta (~20-22 degrees f) would mean the fill would stay toward the deep end, and pump was on the steps. The pump is so much faster than the hose that I think the missed opportunity is pretty small. I’ve also read that CYA tends to accumulate lower in the pool, so maybe I had it all backwards.

 

[mknauss]

’ve also read that CYA tends to accumulate lower in the pool, so maybe I had it all backwards.

Just want to state that is false.

 

[mgtfp]

I’ve also read that CYA tends to accumulate lower in the pool, so maybe I had it all backwards.

You probably mixed some information here. What can happen is this:

When closing a pool for winter, fresh rain water will not get mixed with the already existing water (due to the pump not running). Since pool water contains salt (even non-SWG pools relatively quickly accumulate more than 1000ppm of salt because added chlorine eventually turns into chloride, aka salt), it's density is higher than that of rain water, so that fresh rain (or melt) water keeps floating on top.

That's why it's important to run the pump for a while after opening the pool for the season before testing, panicking and adding anything (not just CYA).

But generally, CYA is homogeneously mixed throughout the pool.

 

[milesandmiles]

Some progress - CYA is down to 120 from 160 (using the same person/process… tho it seems a bit prone to error). I tested levels and added acid and liquid chlorine per Poolmath suggestion. Almost. For some reason I paid attention to the Muriatic acid % but not the Chlorine. Added 10% chlorine at the 6%-recommended levels. Still feeling like a successful first week at the helm.