New test kit, horrifying resutls

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piratespoint

0
Mar 12, 2013
30
Cayman Islands
My new test kit came and some of the results I got were a bit disturbing.

Ph 6.8
TA 110-120
CL a bit low, but I can fix that
CH couldn't get a handle on this one. Either it's way too high, or I'm doing it wrong.
CYA 180 is my estimate. I could only get about a quater inch of water in the tube before I couldn't see the black dot anymore. 150 is as high as the indicators on the tube read.

Am currently waiting on an order of chemicals. We don't have a pool store here, so I'm getting by with what I have. I've been using some bleach to offset the amount of tri-chlor pucks I use, but the CYA is so high that I fear I may have to drain most of the pool to get it back under control.

Also am using Borax when I can get it to raise the PH. Some weeks I get some, some weeks I don't. Have been out of PH up/soda ash for some time now. I've also rigged a garden hose with a sprayer so I can aerate the water as I fill it. I'm hoping this raises the PH as well.

The algae is getting bad. The black algae is the worst. I have to go in on scuba and scrub it with a wire brush, then come back and rub chlorine directly on what's left. I think the CYA is so high that the chlorine is nearly ineffective and the algae is taking over. Currently have nothing to treat it with.

The filter grid also has a hole in it and we've run out of replacements. They've been going at regular intervals now. I fear that the water chemistry is so harsh that it's burning them up. Either that or after five years sitting around they're a bit weak. New ones are coming on the order, whenever that gets here. Been waiting since October.

Any advice would be quite welcome. Thanks for taking the time to read this. :-D
 
Dilute by 50% (1:1) with tap water on the CYA test and run it again. It that doesn't get you to a real number dilute further (1:2 or 1:3) don't forget to multiply by the dilution rate to get your real CYA number.

Until you have a good CYA number ... not much we can help with.

once you have a good CYA number you can use the calculator to see how much of the water has to be drained to get it under control.

on the CH - if the CYA is that high odds are the CH is through the roof as well, fortunately its the same solution - drain and fill.
 
I am using a TF-100 kit. I've diluted the water by 1/2 and was still well off the chart, so went back and diluted into thirds. Still off the chart, but I can estimate maybe around 400ppm on the CYA. I am going to try to talk the boss into draining the pool during hurricane season when we are closed this fall.
 
With a CYA at 400 your target CL is between 34 and 48 - if your CL is at 4 that is 30 GALLONS of bleach ... not to mention you will sear the skin off anyone that gets in the pool.

I would encourage the boss to drain and fill now. Giving SCUBA divers ear infections from a bad pool is really bad for business.

Chris
PADI AOW since 1994
 
karmabiker said:
With a CYA at 400 your target CL is between 34 and 48 - if your CL is at 4 that is 30 GALLONS of bleach ... not to mention you will sear the skin off anyone that gets in the pool.
Click to expand...

No you won't!!!! Because the CYA is so high.
A FC of 40ppm at a CYA of 400ppm is the same as a FC of 10ppm at a CYA of 100ppm ... or a FC of 5ppm at a CYA of 50ppm.

Back to Pool School!!! ;)
 
jblizzle said:
karmabiker said:
With a CYA at 400 your target CL is between 34 and 48 - if your CL is at 4 that is 30 GALLONS of bleach ... not to mention you will sear the skin off anyone that gets in the pool.
Click to expand...

No you won't!!!! Because the CYA is so high.
A FC of 40ppm at a CYA of 400ppm is the same as a FC of 10ppm at a CYA of 100ppm ... or a FC of 5ppm at a CYA of 50ppm.

Back to Pool School!!! ;)
Click to expand...


ARRRRRRGGGGGHHHHH.

:hammer:

I think I got it - so no searing of skin just TONS of bleach to get to a level that actually sanitizing the pool? I think the part of the equation I missed was that the FC is the only reactive component.
 
karmabiker said:
I think I got it - so no searing of skin just TONS of bleach to get to a level that actually sanitizing the pool? I think the part of the equation I missed was that the FC is the only reactive component.
Click to expand...

Well, most of the FC is bound up with the CYA. The "active" chlorine is much less than the FC. See this chart which show just how much more harsh a public pool with 2ppm FC and 0CYA is compared to the levels we recommend:
http://richardfalk.home.comcast.net/~ri ... l/HOCl.htm
 

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Just so you know, technically the chlorine bound to CYA is teensy-weensy reactive -- about 1/150th as much as hypochlorous acid. We generally ignore this because the FC levels aren't usually that high. Nevertheless, even accounting for this, 40 ppm FC with 400 ppm CYA would still be quite a bit less strong than commercial/public indoor pools with 1 ppm FC and no CYA.
 
To save your reagent when CYA is high just mix a small amount of the water you are testing, 50/50 with reagent. You don't need to mix a full sample since 10 ml (5 and 5) will yield results on anything above 60 ppm and 20 ml anything above 35.
 
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