Draining to lower CYA...Help...

[Ecoke]

Hey Folks...I need your help. I'm in the process of draining about 9,000 gallons to lower CYA from 160 to 60-70...I have been drawing from the main drain....hose to street and return to my spa...I'm down about 18" and now this...

I am below my vacuum suction line...and the pool returns and obviously the skimmer....all has been fine until now..I went to check on it...pump was dry...don't think it has been for that long..was not really overly hot to touch...I tried to fill basket and start pump...no good...I am not drawing suction...all was fine when I started back up this am..had been below my side suction line with no problems...last night and when I started up this AM...

Any ideas on why all of a sudden this happened????

 

[Jimrahbe]

E,

Main Drains, despite the name, really aren't good for draining a pool. Your problem is what often happens.

I suggest you rent or buy a submersible pump to finish the job.

Thanks,

Jim R.

 

[Ecoke]

oh brother....Believe in the process....(thinks to self)

 

[zea3]

Quite a few pools are plumbed so the skimmer line and the main drain are connected. It helps to prevent entrapment on the main drain if it becomes blocked, but it also allows air to enter the system and you will lose prime when draining just as you have seen. Purchase or rent a submersable pump to finish, or refill, restest and see if you need to drain more. If you ever need to drain the pool this low again, attach a pool vacuum head and attach it to the skimmer as if you were going to manually vacuum the pool and let the vacuum head rest in the deep end. That will keep air out of the skimmer while you drain the water.

 

[Ecoke]

Thanks Zea3...I have a vac...I guess I can attach it to the skimmer..and rig hose to bottom of the pool...I didn't think of that..and thus..Why I asked you folks!

 

[Ecoke]

Is this scaling?? Calcium being pulled out of walls or is it being deposited from the water due to high calcium levels (420)?

I have a Diamond Brite finish..was cleaning rust off surface with spritz of MA...noticed the color popped. Will this brownish cast go away nce my pool chemistry is fixed per TFP guidelines?

if no and I spritzed area above water line with MA...would be a noticeable variation line in color...not good...thoughts?

will post 2 pics..

 

[pinguy]

Not sure about the second photo, but the first definitely looks like calcium. You can clean it with a weak MA solution.

Deposits come about on tile like that due to high calcium levels coupled with unmanaged pH/TA. High calcium can be managed by keeping pH in the low end of the reccomended 7.2-7.8 range, and keeping TA on the low end as well. This is where the CSI (calcium saturation index) section of Pool Math comes in handy. CSI is calculated from pH, TA, CH, and water temp. Keeping CSI between -0.6 and 0.6 will prevent scaling or leeching.

Your water replacement will bring down CH as long as the fill water has a lower CH than the water you're draining. Having a plaster pool, you want a CH level 250-350 to prevent leeching.

Pool School - Calcium Scaling