CYA problem - emptying pool? Need advice

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T

trivetman

Bronze Supporter
Jul 14, 2017
751
Jenkintown, PA
Pool Size
24000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Hi All -

Newbie here. Owned my pool for three weeks (came with the house I just bought) and we have high CYA - seems obvious that the pool has been chlorinated exclusively with trichlor for a while from the chemicals left for us in the garage.

So I finally got my first test kit to get an accurate measurement (Leslie's water testing gave us the first indication of high CYA) and it's about 130-140 ppm (measured 65-70 ppm at 50% dilution). I was planning on doing a partial drain and refill to fix the problem but now that I see how high the level is I am wondering what my options are. The biggest problem is I have is very limited options to drain to. It's a suburban neighborhood and I'd rather not flood out my new neighbors. The township guidelines are to drain into the sanitary sewer. I can do that with a submersible pump and garden hose into the basement drain but it is going to take most of the day if I need to drain 18000-19000 gallons (75%-80% for target 30ppm). Considering I need to constantly keep an eye on the hose going into the basement watching for overflow, that will be a real time suck.

Also I was wondering if there might be structural issues with draining out that much water and leaving the shell almost empty, even for a short time. Someone told me that empty pools can 'float' out of position.

So, if I instead pump and refill maybe 6000 gallons to at least get the level below 100ppm does that help me? That at least gets the level below what I understand is the 'danger zone'. Then I switch over to liquid chlorine instead of trichlor and maybe repeat the process again a while later, although doing it all at once definitely seems the most efficient from a water/chemical waste viewpoint. I was also wondering about trying the BioActive CYA reducer from Leslie's to help out although it sounds like it's really hit or miss whether it works or not from reading online.

Interesting to note that although the CYA has been so high and our chlorine levels very low since we moved in (mostly from ignorance as we lost track of it), we haven't seemed to have any problems with algae growth or anything visible in the water.

Advice?? Thanks
 
Not yet :). I have seen where people have done multiple drain/ refills to get to their goal... problem is each time you are diluting what you are draining... But it can help you get to where you need to be...

Luckily, I have a storm sewer manhole at the back corner of my yard. I can pull the hose in it and pump forever :)
 
Well I havent been through that process yet but from what I've gathered it'll need to be drained a bit below the skimmer/coping level. Not a huge dent in the total pool volume. But thats kind of what I was thinking too. At least reduce the concentration some now and with backwashing and then some draining for the winter we'll see how much that eventually reduces the concentration
 
My advise is to do partial drawn downs and refills over the season and gradually bring down the cya level. In my first year using the TFP method, I managed my high cya (140 -160 ppm) over that summer while doing strategic drawn down of the pool water level prior to rainstorms and using pool water to water my grass. Using this method, I was able to get my cya down to around 70 -80 ppm by the end of the seasons. With further draw down at closing time I was able to get my cya in the 30 ppm for the start of the next season. So it is manageable, but you need to keep your FC up to the levels that are consistent with the cya level. Once at the appropriate level, then you are only replacing your daily loss. The one risk is that if you do loss control and get an algae bloom, then you will need a high level FC to slam the pool.
 

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You can manage a pool with high CYA, you just need to keep chlorine in the correct ratio. Use [FC/CYA][/FC/CYA] to determine your FC level. Do a series of small drain and refill cycles throughout swim season to bring CYA down over time. Since you do not need to slam the pool you can manage with higher CYA levels. Do you have a saltwater chlorine generator? If not use only liquid chlorine in the pool, either 10-12% chlorinating liquid or 8% plain, unscented grocery store bleach. Use PoolMath to determine how much you need for your pool.
 
I have seen a way of a drain and refill on here without mixing and draining down
Get a large tarpaulin that will cover the pool and reach to the bottom start filling on to the tarp which will displace the pool water keeping the two separate
When you have finished draining put one side of the tarp in the water and pull the other side out
You have safely changed your water at the minimum expense and time
 
Hi trivitman,

From one Newbie to another.....I too recently moved into a new, old house with a pool and a high CYA level of 160ppm. I posted a thread in the "introduce yourself" forum if you want a play by play with pictures.
I did not notice any green color and only a slight haze at night with the pool light. I did notice a nightly deposit on the pool floor I hoped was pollen but now realize was algae. As I learned more about pool chemistry I raised the FC to compensate for my high CYA and was spending $15 a day to maintain my FC. I was killing some of the suspended algae but not fully and the FC levels required to SLAM the pool were so high I had doubts it would ever happen. My overnight Free Chlorine loss was significant at 6+ppm, my sanitizer costs were high and there was not end in sight so I decided on the advice of several folks here, to move the water out and properly get a handle on the situation.

Confirm if you have an issue first but know that you are on borrowed time with high a CYA number and I would not count on reducing it with bacteria. The overnight Free Chlorine test will give you an idea of your bio-load and how hard your chlorine is working.

I too live in a suburban neighborhood and needed to get the permit from Public Works and notify Flood Control. The process was painless and online, they even asked about the CYA levels which I was able to answer. I was allowed to run the water out the driveway into the street but was cautious about letting the water get too high up into my neighbors yards before moving it around. There are only a few small puddles around the neighborhood this morning and nobody is yelling at me.
An electric submersible pump will pull about 3,000 gals per hour. I opted for a gas powered 2" pump and it drained my pool in 6 hours so 5,000 gal/hour at just above idle. The upside about draining in summer is that things are dry here, evaporation is high and the trees can use the water. The down side is not using the pool when it's hot and being careful not to keep it dry too long. I was able to drain and refill in 24 hours.

Regarding the pool lifting out of the ground, this is an effect of high groundwater that floats a now light weight empty pool, check to see what the water table is in your area and be cautious about that and possible effects on the plaster.
You are right to be nervous about pumping into your basement drain and you may want to get a water sensor alarm and secure the hose to the drain somehow.

Folks here are eager to help it seems so keep asking questions until your confidence grows, then take charge. Have fun and keep us posted.
 
I am generally an outlier when it comes to high CYA. I agree with zea, it can be managed and worked down over time.

I too bought a house with a pool and from the chemical trash left behind they pool had existed on a diet of pucks and Dichlor shock. The pool stores were useless because they told me the CYA was in the 80 - 100 range and not to worry about it, their OK level was 250....

I was lucky because I purchased lat in the year and the water was already getting cold so I had the winter to learn. Well, I found TFP....

Once I got my test kit through diluted testing I discovered my CYA was 250ish. Thing is, once you start diluting the test you also increase the margin of error in the test.

So, what did I do.
  • I switched to bleach. BY hand at first, then I installed a Stenner Pump
  • I back-washed my filter often, just because I wanted to.
  • I did many small water drain/refills, usually just to the bottom of the skimmer before it started sucking air.
  • I installed a downspout diverter to harvest rain water. Kind of like this one Downspout Diverter, Rain Barrel Diverter | Gardener's Supply But I rigged up a system where the water dumped into a bucket first, then went into the pool so that trash from the gutters would go in the bucket, not the pool.
It took about 18 months of work, but I am now at the point that I not only buy CYA and add, I use pucks at times also.

The one thing to keep in mind, the pH test reads incorrectly high when the FC is above 10. I had to play some games because of that, but you are in better shape. With a CYA of 140 your minimum FC should never go below 10.5 (7.5% of CYA). So, after a few times of letting your FC drop a little to get an accurate pH you should be able to understand your pools appetite for muratic acid.
 
All - thanks a lot for the advise. I'm going to give the CYA reducer a try because if it works it saves me a whole lotta headache and if it doesnt work it is only a little time wasted. And so far I havent had anything growing green in there so I am hoping my luck holds out. If that doesnt do the trick probably a series of drains over the next couple of months. Ill let you know if the cya reducer does anything.
 
trivetman said:
All - thanks a lot for the advise. I'm going to give the CYA reducer a try because if it works it saves me a whole lotta headache and if it doesnt work it is only a little time wasted. And so far I havent had anything growing green in there so I am hoping my luck holds out. If that doesnt do the trick probably a series of drains over the next couple of months. Ill let you know if the cya reducer does anything.
Click to expand...

I hope for your sake it does work, but we have seen very lackluster results from members who have tried the Bio-Active, so don't be surprised if you do not see any results either.

Be forewarned, you will need to lower your FC levels below safe minimum while you do this, a very possible invitation to an algae party. If this happens you'll be forced to drain to get CYA to a level that is manageable to SLAM Process. You may want to consider a polyquat algaecide to supplement during this period.

IMHO, it would most likely be quicker, and more cost effective to just bite the bullet now and drain.

Good luck, keep us posted.
 

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