Help - draining to lower CYA

[fishbait]

Now is the time for me to get the pool corrected. The previous owner used chlorine tablets exclusively and from their instructions they said to add one to the skimmer every two weeks. I ignored this and have been using liquid chlorine to adjust. The tabs had CYA in them, so my CYA is in the 140 range.

CYA - ~140
TA - 80
CH - 270
FC - 15
PH - 7.6

17500 gallons. My math tells me to drain and refill around 12,600 gallons to get CYA to ~40. I'm guessing the 1.5 HP superpump does about 80-100 GPM? Is that close?

No idea how long it will take with an average garden hose to refill. Any ideas?

After I refill, what is the sequence for tuning the water chemistry? Is it an automatic SLAM after a refill? Do I adjust everything but chlorine first and then do the SLAM? Or, since it is drinking water, do I just adjust the chlorine as per TFP???

How much of each chemical should I have on hand for the initial chemistry balance?

Looking to do this tomorrow if possible, depending on what the fill time might be. Thanks for any help and advice!

Brian

 

[PoolStored]

Fishbait...First, read this:

Draining - Further Reading

www.google.com

17500 gallons. My math tells me to drain and refill around 12,600 gallons to get CYA to ~40. I'm guessing the 1.5 HP superpump does about 80-100 GPM? Is that close?

Don't know, but it will be higher rate than your fill hose. You might look into a sump pump. Mine, at the deep end is just a bit faster than my fill. I raised the hose over an 8' ladder and the fill and drain hoses closely matched.

No idea how long it will take with an average garden hose to refill. Any ideas?

Typical residential water systems are around 6 GPM. Using 5 to be conservative, it will take 40-45 hours.

After I refill, what is the sequence for tuning the water chemistry? Is it an automatic SLAM after a refill? Do I adjust everything but chlorine first and then do the SLAM? Or, since it is drinking water, do I just adjust the chlorine as per TFP???

This is hard to answer. Take your test kit and test your input water. That will give us some idea of what you are putting in, and what you might need to do. You can test and add LC as necessary to keep your FC up.

How much of each chemical should I have on hand for the initial chemistry balance?

Again, without knowing your fill water hard to tell. The most important thing is LC.

 

[Rancho Cost-a-Lotta]

I'm guessing the 1.5 HP superpump does about 80-100 GPM? Is that close?

Where do you plan to run the discharge? If running into a sewer cleanout, you don't want to exceed 700 GPH. If running into the street, your pump will create a river. Make sure you check local regulations for how to handle pool discharge.

You can't use the pool pump for most pools. Once water drop below the skimmer, your pump will just be sucking air. If you're plumbing allows you to isolate suction from the main drain, you may be able to do it, but you still run the risk of sucking air and running the pump dry.

It's best to use a submersible pump.

You can estimate fill rate by timing how long it takes fill a 5-gallon bucket with your garden hose.

 

[Mdragger88]

Did u do the diluted cya test to confirm this cya level? Step 8

CYA - Cyanuric Acid Test

Cyanuric Acid (CYA) is the chemical name for what is commonly referred to as Stabilizer … Read more…

www.troublefreepool.com

 

[fishbait]

Where do you plan to run the discharge? If running into a sewer cleanout, you don't want to exceed 700 GPH. If running into the street, your pump will create a river. Make sure you check local regulations for how to handle pool discharge.

You can't use the pool pump for most pools. Once water drop below the skimmer, your pump will just be sucking air. If you're plumbing allows you to isolate suction from the main drain, you may be able to do it, but you still run the risk of sucking air and running the pump dry.

It's best to use a submersible pump.

You can estimate fill rate by timing how long it takes fill a 5-gallon bucket with your garden hose.

My discharge runs underground and into the woods on the edge of my property. From there, it runs downhill away from my house to a drainage ditch.

I can isolate the skimmer / main drain. I can also put a plug in the skimmer to prevent air entering. After that, there is about 6 feet of head to the main drain. I think I can take it down pretty far with the pump, but who knows.

I will do the 5gallon bucket test. I wasn't planning on 40 hours of filling! Might have to consider a water truck or something.

Did u do the diluted cya test to confirm this cya level? Step 8

CYA - Cyanuric Acid Test

Cyanuric Acid (CYA) is the chemical name for what is commonly referred to as Stabilizer … Read more…

www.troublefreepool.com

Yes, several times over the last several months. It's the only way I can measure since the level is so high. Will do a final one tonight to see if it has dropped at all over the winter.

 

[Rancho Cost-a-Lotta]

I can isolate the skimmer / main drain. I can also put a plug in the skimmer to prevent air entering. After that, there is about 6 feet of head to the main drain. I think I can take it down pretty far with the pump, but who knows.

If you go this route, stay close and monitor the pump for air/cavitation. Sounds like you've thought things through.

 

[fishbait]

So, did a double test and found that over the winter my CYA has dropped from 140 to 60. Is this normal for it to fall. Sure makes my life easier if normal! All other test were in range of TFP recs, except CH which is 190. Is 450 really the rec?

 

[mknauss]

Sounds like you got a lot of rainfall and drain out. Indicated by the CH loss.

You should get your CH to 300 ppm or so at least.

 

[fishbait]

Sounds like you got a lot of rainfall and drain out. Indicated by the CH loss.

You should get your CH to 300 ppm or so at least.

I hope that's the case, but I have no overflow, just normal backwash every one in a while. Pool was covered all winter. Never had to add water. Is there any other thing that would cause CH and CYA to drop? Maybe I'm just paranoid.

 

[mknauss]

CYA can degrade some. But CH will only leave if you drain water. Or your pool is now covered in scale, which I doubt is true.

 

[fishbait]

CYA can degrade some. But CH will only leave if you drain water. Or your pool is now covered in scale, which I doubt is true.

Not seeing any scale. I think I'll just consider myself lucky to have CYA lower so much and go from there. Will do another round of tests today just to confirm. Thanks for the replies! I'm thinking of converting to.salt and picking up a SWG. If I remember, CYA levels are recommended higher with SWG, is that right?

 

[mknauss]

If I remember, CYA levels are recommended higher with SWG, is that right?

Yes. 60-80 ppm CYA is a good range for a SWCG.

 

[Keyan]

Not seeing any scale. I think I'll just consider myself lucky to have CYA lower so much and go from there. Will do another round of tests today just to confirm. Thanks for the replies! I'm thinking of converting to.salt and picking up a SWG. If I remember, CYA levels are recommended higher with SWG, is that right?

I’ve had this happen. My CYA levels went from higher than they probably should have been (I didn’t know to watch it super closely) to zero over a winter. At open, there was zero free chlorine and no CYA and the water was extremely cloudy. Ammonia levels through the roof. Adding solid shock created a violent chemical reaction. 30+ gallons of liquid shock later the ammonia was burned out and free chlorine started to register. Apparently there is a microbe that can convert CYA to ammonia. Same thing happened again this year but we tested and caught it before the season started and all of the CYA was gone. Now my levels are high again so it’s back to the dump and replace for some water to get it down.