CYA test dilution?

[october_affair]

Hello,
I just started using the TF100 test last week and when I first tested the water, the CYA was over 100 and the CH was 800. Somewhat puzzling, since we almost drained the pool before closing last year and replaced more than half of the water when we opened it this summer. Granted, we have been using stabilized chlorine (dichlor and trichlor), but that is pretty much it. From what I have been reading at the forum, it shouldn't have raised the CYA that much (since I have shocked the pool only twice) and why the CH is so high, I have no idea. I have added borax and baking soda during the summer and nothing else. I have a 30 000 gal. plaster pool, Triton sand filter and the water has been crystal clear the whole summer. I do see some spots on the plaster, but I can't tell if that is algae or not. I have been brushing both with regular brush and algae brush and do not see any change whatsoever.

First day test:
FC 5
CC 0.5
PH 7.6
T/A 50
CH 800
CYA 100+ (I couldn't see the dot any longer to approx. where 120 mark would be)

I added bleach in the morning, brushed the pool and tested the FC at 10.5, CC was 0 at that point, let the pump run for 12 hours, retested FC/CC in the evening at 8/0. The next day drained the pool to the skimmer basket once, filled it up with water, let the pump run for 12 hours, the following day drained it again to the skimmer, filled it up, the filter has been running for 12+ hours at this point and I retested today again, day 4:

FC 6 (I have not added any bleach or anything in the past 4 days, so this is down from the 10.5)
CC 0.5 or less
PH 7.2
T/A 90
CH 500
CYA 100+: so I looked around the forum and found a recommendation to dilute the test for CYA, but couldn't find any directions as to how. I took 7.5 ml pool water, mixed it 7.5 ml tap water and added 7.5 ml test, mixed that and the reading was 90. The tread at the forum said to double the result...does that make the CYA 180? Or did I just get the dilution wrong?

My plan of action at this point is to keep draining the pool daily to the skimmer (I am ashamed to say that I have not figured out yet how to drain the pool, other than backwashing through the filter) and adding water and once I get the CYA down the 80, adjust the rest of the chemistry. Is that the way to go or should I be doing something else?

 

[duraleigh]

First, welcome to the forum!!

Secondly, the dilution method you used was close but not quite correct. Use 1/4 tap water, 1/4 pool water and 1/2 reagent.

Nevertheless, it seems pretty obvious your CYA is really high so here's how you can drain it more quickly.

If you can get a drain hose down to the bottom of your deep end and start a siphon, simple start filling your pool from the surface of the shallow end. The siphon will drain 100+CYA pool water from the opposite end of the pool as you refill with 0 CYA water from the other.

This will also help reduce your CH as well which is testing very high. It may be helpful to get confirmation of your numbers from a pool store, but if they differ widely, the chances afre your numbers are correct.

Keep us posted.

 

[meatloaf]

If you can get a drain hose down to the bottom of your deep end and start a siphon, simple start filling your pool from the surface of the shallow end. The siphon will drain 100+CYA pool water from the opposite end of the pool as you refill with 0 CYA water from the other.

Are you saying that CYA saturated water is actually heavier or denser than water with lower CYA?

 

[duraleigh]

Are you saying that CYA saturated water is actually heavier or denser than water with lower CYA?

Nope. (although it might be...I don't know) I am simply saying seperate the two hoses as far from each other as possible.

However, since you brought that up, it might make more sense to siphon near the top of the water and place your refill hose down deep. Colder water is definitley more dense than warm and it would certainly follow that your fill water would always be colder and stay near the bottom as you siphoned the warmer water off the top.

 

[october_affair]

I had my water tested twice in the local pool store in the past 2 weeks and according to them, everything was fine. Their computer didn't measure the CYA though, but the CH was in check...that is why I was questioning my results initially and wasted half of my kit retesting the CYA and the CH. I will start with the drain again tomorrow. Thanks for clarifying the CYA dilution, as I am almost out of reagent

 

[Guest]

I had my water tested twice in the local pool store in the past 2 weeks and according to them, everything was fine. Their computer didn't measure the CYA though, but the CH was in check...that is why I was questioning my results initially and wasted half of my kit retesting the CYA and the CH. I will start with the drain again tomorrow. Thanks for clarifying the CYA dilution, as I am almost out of reagent

If they used a computerized water test that read a vial with a meter that type of test does have some limitations, particularly for CH, and can read low when the test results exceed the range of the meter (usually around 400-500 ppm)