CYA test off the chart

[surfhawaii]

Hi...my first post, thanking responses in advance.

From Taylor kit test my CYA level doesn't even come close to 100 mark which, since scale is inverted, I'm assuming it means it's around 200 or so. Tested twice, same result. From what I've read here the only way to lower this is to drain and refill. Question is, how much to drain? I know the answer will probably be 'it depends' but for a ballpark, is that 1/10 of the pool, 1/4, etc.

Other test results show pool needs some chemicals (need to raise ph, etc.) but if I'm going to be draining/refilling, doesn't make sense to try to work on other stuff until I get CYA under control because I would be losing new chemicals anyway, correct?

Thanks.

 

[JohnT]

Welcome to TFP!

Unfortunately, that probably means about half the water. You can get a ballpark idea of where your CYA really is by using twice as much water and doubling the reading. It's not highly accurate, but will give you an idea.

 

[jblizzle]

The "simple" answer is ... depends on what level you want :lol:

If you replace 50% of the water, your level with drop by 50%. If you replace 75% of the water, your level will drop by 75%.

This assumes you do it all at once. If you do smaller drain and fills, it will take more water replacement to get to the level you desire.

If you are at 200 (not really easy to determine), I would guess you should replace 75% of the water to get close to 50 and then retest and adjust again as needed.

ETA: I would think you would be best getting the CYA level correct through water change(s) before adding a "bunch or other stuff". Although you should maintain enough FC so that algae does not start to grow in the process.

 

[surfhawaii]

Thanks for prompt response but, was afraid you'd say this. Next question is since I'm a newbie to this, what is most efficient way to do this, run the pump while refilling with water (seems this would lose some of the new water I was putting in), get a pump to empty it, etc.? And, just curious, assuming this didn't happen overnight (or does it?) since I just took over maintaining pool from pool service, shouldn't they have been testing/moderating CYA?

 

[JasonLion]

There is relatively low awareness in the industry of the problems of high CYA levels.

You need to replace water to get CYA down. The quickest way to do that is to run the pump on backwash while filling from a garden hose. The pump will probably pump out faster than the garden hose will fill, so you probably need to turn the pump on and off occasionally to keep the water level from getting below the skimmer. This is not perfectly efficient, but it is very easy. To be more efficient, you need to pump the water level down several feet and then refill, which that can be tricky unless you have a main drain and can turn off the skimmers.

 

[jblizzle]

I currently have a "pool" company and I am pretty sure my CYA is up at your levels ... they think it is adequate to come by once every 2 weeks and pump some gas in the pool. So the FC goes sky high and then drops for 2 weeks ... thus they need the high CYA I guess. I too am getting ready to oust them and take over, probably with a SWG, so I will also have to change over 50% of my water.

Regarding the water change, ideally you do not want to be adding while you are removing and the addition will dilute what you are removing resulting in more water change required. If you can isolate you main drain, I guess you could use that to empty. I have in the past rented submersible pumps from Home Depot (not sure that is an option for you).

NOTE: care need to be taken when draining the pool. If the ground water table is high, your in ground pool (although I guess I assumed that) could pop out of the ground. That is why some people recommend multiple smaller water exchanges (also required if you have a liner pool I guess).

A side conversation on jblauert's issues has been moved to this topic. JasonLion

 

[Isaac-1]

How to best do a water exchange depends on a number of factors, type of pool, water table (can you drain at once without having to worry about your pool floating up), etc. If your fill water is colder than the pool water (often the case with private wells in the summer in most areas) the fill water will tend to sink to the bottom, so if you drain from the surface while filling cold water at the bottom and not circulate the water it will tend not to blend as fast.

 

[Txmat]

I do not have a main drain so when I was faced with having to drain a couple of feet of water I put a hose a vacuum hose into the pipe leading from my skimmer to the pump and pumped to waist. If you are not worried about draining too much water at a time the same technique might work for you.

 

[zea3]

Back to the original question! Surfhawaii, you may need to drain more than once to get the CYA level where you need it to be. Also, you need to decide how you will chlorinate the pool in the future. Do you plan to continue using liquid chlorine, or do you plan to add a saltwater chlorine generator? If you choose the swg, then you will keep the CYA around 70-80 ppm. For liquid chlorine you will drop down to 30-50 ppm.

You could use the manual vacuum set up and filter set to waste to pump water out of the pool. Set the vacuum head in the deepest part of the pool. Drain about 1/2 the water and refill. Circulate the water for an hour or two then test CYA to see if you need to drain any more water.

 

[surfhawaii]

Thanks for all the replies, I need these discussions because I'm new at this. Went to local pool place and had them perform test just to make sure I was doing it correctly and they got same results and said same thing as you guys...drain the pool. They rent submersible pumps and they're recommendation was to just drain the whole thing because concentration was so high. Although I'll have to pay for water, might be just as easy with strong pump.

They also recommend using chlorine tabs that are 99% chlorine instead of the ones I'm using (pooltime) that also have a stabilizer in them. They also recommend doing test for phosphate. So, questions for you experts:
Agree with 99% chroline tabs?
Agree I need to do phosphate testing?
And, do you have recommendations on what chemicals I should add once water has been totally replaced?

Thanks again.

 

[Bama Rambler]

Here's my thoughts.
1) If it's a tablet is has either CYA, calcium, or lithium in it. I'm not sure what they're recommending but it's going to add one of those if it's in tablet form. Find out which and post back.
2) Don't waste your time on testing for phosphates. If they test for it they're going to try and sell you something to correct it, when in reality it's irrelevent. Maintaining proper FC levels will keep algae from starting at all, and you have to have that for a sanitary pool anyway.
3) You need to test the water (or the fill water) and use the Pool Calc to figure out how much you need of what. The only sure thing you're gonna need is chlorine.

 

[bobodaclown]

I bought a $100 sump pump from HD and some hose to drain my pool. I've got a cartridge filter and it only has a 5/8 drain on the top. Worked well. Change about 1/2 the water to get approx CYA=100.