First Test - Now What?

[Rtlesq]

Hello All:

I came across this great website after being unable to maintain any chlorine in my pool for the last month or so. I'm a new pool owner, and I've been using cheap test strips and trichlor pucks -- on the advice of the previous owner -- since buying the house/pool last year. When the pool was opened this summer, it seemed to have plenty of chlorine per the test strips, but since then I haven't been able to keep it to a visible level no matter how many pucks I add.

So, I bought the Taylor K 2006 Test Kit and did my first test this afternoon. Here are my results:

FC: 0
CC: 0
CYA: ~250 (I had to dilute the sample twice to get a reading below 100; the dot disappeared at around 60 with the 2x diluted sample)
pH: 7.0
TA: 70
CH: 250.

I know from reading the forum that I'm going to have to drain the pool quite a bit to get the CYA to the right level, and I've already purchased 10 gallons of liquid shock from my local Menard's. The pool water appears very clear and I don't see any algae or mold. But, it's a black, gunite surface so maybe I'm not seeing it.

My question is: how much of the pool will I have to drain and refill before I get the CYA level to around 50? Is there anything I need to be concerned about (other than my water bill) if I drain the pool nearly all the way? As best as I can tell, the pool is about 18,000 gallons, oval shaped, with a max depth of about 6.5'. It has a waterfall that I run occasionally, but not full time. It's equipped with a Pentair cartridge filter with 4 brand-new cartridges I installed about a month ago.

Thanks in advance!

 

[ajw22]

Welcome to TFP.

You need to drain around 80% of your water to go from CYA 250 to 50. Draining any pool that much can be a risk depending on the height of your water table.

@mknauss can provide how to do a water exchange.

What is the pH, TA and CH of your fill water?

 

[mknauss]

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.

 

[Flying Tivo]

You will need to drain 90% of the water to get it to 30ppm. Make sure you dont have a high water table and temperatures are not high.

 

[Rtlesq]

Thanks, all. I'm seriously considering getting my local village fire department to come in and pump out the water and then refilling it with a fire hose attached to a fire hydrant. Apparently, this is an option here in the area where I live just outside of Cincinnati. In that case, I think the pool would be at 10 - 20% filled for only a short time. But, it's been extremely hot lately - 90ish - and the pool is in direct sunlight basically all day. How much risk is there of damaging the gunite if I use this method rather than the exchange method mentioned by @mknauss above?

 

[ajw22]

If you pump out the water and immediately refill in a few hours your risk should be low.

 

[Flying Tivo]

You can also use a sprinkler to keep the walls wet.