Advice needed! tested water b4 taking cover off.. CYA is 350

[acamato]

I have a 21,900 gal vinyl lined pool. I moved into the house in late July and just used the chlorine tabs the previous owner left me. When I closed the pool I just shocked, added algecide and covered the pool and forgot about it. After finding TFP I learned alot and I am going to do BBB....

Here is my issue...

I tested my water (with the cover still on) with a test strip (I know I need to order a real kit) I will take a sample to the pool store to see their results. The water looks pretty clear.

here are my results:
Hardness - 250
TC - 1
FC - 0
pH - 6.8
CYA - 350

Here is my plan: drain some water, refill & test CYA repeat untill I get below 80. After I get to below 80, add bleach & adjust pH.

How much can water drain out of my pool? 1ft? 2ft?
Does my plan sound good?

I will never use the trichlor tabs again (unless I need to add CYA) also, I ordered a liquidator :-D .


Pool info:
20 x 40 Mountain Pond (21,900 Gallons)
Hayward Micro Guard Grid DE Filter & Pump
Hayward H300 Heater
Polaris 360

Anthony

 

[duraleigh]

Hi, Tony,

Welcome to the forum. The liquidator shipped yesterday...Thank you.

Wow! That's an impressive CYA # and very possibly innaccurate because of the test strips. The pool store will hopefully give you somewhat lower results. Either way, it sounds like you have a bunch of CYA to get rid of.

Several rules of thumb on max drainage of a vinyl lined pool....

1. Not more than 50% of the water

2. Not less than 1 foot below the skimmers

3. Leave at least 1 foot of water in the shallow end

That's all good advice from which you should be able to judge how low to get yours. I particularly like leaving a foot of water in the shallow end. On a vinyl pool, it's mandatory that you keep some pressure (water) on the liner at all times so the liner won't float away from the floor or walls.

Your plan is a good one. I think a CYA of 40-60 is a slightly improved target for a non-SWG pool.....80 is a bit too high.

Also, go ahead and bring your pH up to at least 7.0 now. 6.8 is a little low and it could actually be lower with the limitations of the pH test. It'll cost very littl in borax to move it up into the safe range even tho you'll be draining some of it out.

Re-check your gallonage or pool size....one or the other seems a little off. A typical 20 x 40 pool has 30-35k in it.

 

[JasonLion]

Welcome to TFP!

The water test numbers can be way off if you have not been running the pump. You should test the water again after the pump has been running for at least an hour, unless it already was for your previous test. It would also be good to get a TA number.

If the PH is actually below 7.0, you should get the PH up to 7.0 or higher right away, before doing anything else.

You can nearly always drain down 18", unless the water table is very very high and you have totally water saturated ground. If the water table is reasonably low and you have a vinyl liner you can drain till there is one foot of water in the shallow end. I you have gunite/plaster/pebble you can drain down to the water table level (if you know what it is).

Keep in mind that the test strips are not especially accurate. I have no doubt that your CYA level is too high, but given a strip reading of 350 it might actually be anywhere from 200 to 500. The good CYA test only works up to 100, so you will need to use the strips for now, but when the CYA level gets lower use the better test to make the final adjustments.

 

[chem geek]

I'm just curious what kind of algaecide you used and whether you know if the previous owner used any algaecide (any bottles left around)? Not every pool with low FC and high CYA will get algae, but something about your pool has prevented it and it could be the algaecide or a lack of nutrients (phosphates, nitrates). I just wonder if a copper algaecide has been used.

 

[acamato]

Thanks for the advice. I will get the pump running tonight or tomorrow, add some borax and then retest the water. I need to do some minor plumbing & remove the plugs in the returns. I cracked the a 1-1/2" union on the in line chlorinator. I am replacing it with a piece of 2" pipe. It should be fun, I only have about 1/2" of PVC showing between the union and the Jandy valve, on both sides of the chlorinator. It is a good thing that the Jandy valve can use 2" pipe also.

I called to company that installed to pool for the gallonage and thy looked it up. It is a Mounatin Pond shape (free form), 20' x 40' at the longest/widest point.

I don't know what algecide I used. I will try to find out. Toward the end of last season I had some minor algae issues, probally due to the high CYA level reducing the FC effectiveness.

I plan on taking the cover off Sunday. I just remembered I also needed recharge the filter with DE. I just wish I was not so busy with other commitments.

 

[acamato]

I got alot done on Saturday. I got the plumbing fixed, pump running & took the cover off. Pool was in great shape, vater was very clear w/ some leaves on the bottom.

I added 6 lbs of DE as per plate on the filter. My filter is running at 9 PSI, does this sound correct? (Hayward Micro-Clear DE with a 1.5 HP Super Pump)

I also added 1 gal of liquid shock that I had left over from last year. I now know better than to waste my money on liquid shock. I also added two boxes of 20 Mule Team Borax.

Here are my test results (still from a strip) . I am going to order a real test kit this week.

Hardness - 150
TC - 5-10 (strip looks between colors)
FC - 3
pH - 7.2
CYA - 30-50

Now I know never to test my water unless the pool had been circulated. Next step get the liquidator hooked up.

 

[JasonLion]

That is looking much better than it seemed to be before!

If the strip is right you have some CC to take care of. CC = TC - FC. But there is no way of being sure of that with test strips. Some extra chlorine and some sunlight will probably take care of it, but if it sticks around you will need to shock.

You should think about getting a top quality test kit. There is no better investment you can make in your pool. The TF Test Kit, see the link in my signature, is a great product and the Taylor K-2006 is also a good choice.

 

[Rockcrawler]

did you backwash

As I was reading your post, I noticed you said you added 6 lbs of DE, did you backwash your filter?? if you didn't then you have to much DE in the filter, and if its a new pool to you, I recommed that you fully disassemble your filter and clean it then add fresh DE, you don't know if the prior pool owners ever cleaned the filter, you don't need to "recharge" your fileter unless you backwash, also you said you added 2 boxes of Mule team borax, did you test to see what level your at, I didn't see any number reflecting borates?

 

[JasonLion]

The borax was to bring the PH up.

 

[acamato]

Re: did you backwash

As I was reading your post, I noticed you said you added 6 lbs of DE, did you backwash your filter?? if you didn't then you have to much DE in the filter, and if its a new pool to you, I recommed that you fully disassemble your filter and clean it then add fresh DE, you don't know if the prior pool owners ever cleaned the filter, you don't need to "recharge" your fileter unless you backwash, also you said you added 2 boxes of Mule team borax, did you test to see what level your at, I didn't see any number reflecting borates?

When I closed the pool last year, I disassembled the filter and cleaned the grid. So, I did need to add the 6 lbs. If I just backwashed the filter I would only need to add 4.8 lbs (80% of 6 lbs)

 

[ChrisL]

You asked if 9 lbs of pressure semed about right. I have a 1.5 hp super pump and a 48 sq ft de filter. My clean filter readings start at about 12. Anywhere from about 8 to 15 should be about right if you do not have a real lot of return pipe with bends. If you do, it may be even higher. A nice low reading probably means your grids are nice and clean. If the flow back to the pool is strong, all is good. If the flow is weak, a low pressure reading could mean a partial blockage before the filter or a problem in the pump.

 

[acamato]

I got my TF-100 test kit yesterday and here are the results: (tested last night)

FC - 13.5
CC - 0.5
TA - 110
CYA - 70
pH - 7.8
CH - 250

My FC is high because I added 8 gal on bleach (6%) on Tuesday night. I alos added 1 gal of 15% liquid shock on Saturday when I opened to pool.

What should I do next? add acid to bring the pH down? or will pH drift down as the FC drops? I will have the Liquidator hooked up tomorrow, it should have been finished tonight but I ran out of tubing. When should I turn on the liquidator? when FC drops to 8?

 

[JasonLion]

Those numbers look good. Don't worry about the PH until the FC level comes down and you test the PH again. The PH will likely be lower when the FC level comes down.

Turning on the Liquidator when the FC level falls to 8 would be ideal. But you don't need to be precise, anywhere from 5 to 10 will do.

 

[acamato]

Thanks for all the advice.