Relatively New to FTP - Need help balancing water...

[Visa1976]

Hi Everyone,

I just received my TF-Pro Salt test kit and ran my first battery of tests. We recently converted to a Salt Water pool using a Pentair i30, and I cannot keep enough FC in the pool. We have algae spots showing up in the bottom in spot-fashion which does not scrub up easily. The water still looks clear. Here are my test results:

Location: North Central Texas
Pool Size ~ 15,000 gallons
Water Temp = 84 F
Salt - 3250 PPM
Comparator Block Test:

• CL - 0
• PH - Above 8.2

Chlorine Drop Test:

• FC - 1 to 1.5
• CC - 1 to 1.5

CYA ~ 90
CH - 450
TA - 150

Thank you in advance for your help! And thanks for all you do to serve us so generously on TFP!

 

[Texas Splash]

Welcome and good job testing your own water. Let's tear the band aid off quickly shall we?

1. You should exchange some water to lower the CYA. In an ideal TFP-clean pool a CYA of 70 is great for the summer, but if you suspect algae, a lower CYA may be better for the SLAM Process "IF" you have active algae. We don't know for sure yet, but I would lower the CYA to at least 70 for now.
2. Once the CYA is lowered, pump that FC up quickly with liquid chlorine. Don't wait on the cell, it's not designed to produce such quick gains. Increase the FC to around 7-8 ppm then do an Overnight Chlorine Loss Test as soon as you can. Report back the results.

If you pass the OCLT, the CYA can stay at 70 and you balance things like normal. If you fail the OCLT, then you'll need to begin the SLAM.

Ignore the CH and TA for now, they're okay.

Definitely lower the pH right away with muriatic acid. Get the pH down to about 7.5 or so to prevent scale.

Hope that helps.

 

[Visa1976]

Thank you so very much @Texas Splash ! I do have a few follow up questions if you don't mind. I'm sure these will show more of my ignorance, so I appreciate your patience on the front end.

First, I now have my PH down to 7.2

I've attached a picture of our pool water so you can see the small appearance of what seems to me to be algae on the bottom in spots. Otherwise the pool is very clear. Does this constitute an "algae problem" or do I just need to SLAM my pool to get the FC up to correct numbers? I guess I'm trying to determine if it is worth trying to SLAM the pool with the CYA at 90 rather than get a submersible pump (I don't have a backwash option) and try to exchange 25-30% of my water to lower my CYA level to 70. What are your thoughts?

Lastly, how long should I wait to test after each addition of Chlorine?

Thank you again for all your help!

 

[Visa1976]

Welcome and good job testing your own water. Let's tear the band aid off quickly shall we?

1. You should exchange some water to lower the CYA. In an ideal TFP-clean pool a CYA of 70 is great for the summer, but if you suspect algae, a lower CYA may be better for the SLAM Process "IF" you have active algae. We don't know for sure yet, but I would lower the CYA to at least 70 for now.
2. Once the CYA is lowered, pump that FC up quickly with liquid chlorine. Don't wait on the cell, it's not designed to produce such quick gains. Increase the FC to around 7-8 ppm then do an Overnight Chlorine Loss Test as soon as you can. Report back the results.

If you pass the OCLT, the CYA can stay at 70 and you balance things like normal. If you fail the OCLT, then you'll need to begin the SLAM.

Ignore the CH and TA for now, they're okay.

Definitely lower the pH right away with muriatic acid. Get the pH down to about 7.5 or so to prevent scale.

Hope that helps.

Would you be willing to help me with my second set of questions above? I'd really appreciate the help. Thank you in advance!

 

[Parac]

The Overnight Chlorine Loss Test is how you confirm if you have algae or not.
If you fail the OCLT and have to SLAM, it is extremely difficult with a CYA of 90. You would want to drain to reduce it. Do a No Drain Water Exchange to prevent the plaster from drying out in the current heat. CYA of 70 may be doable, but it would be better if you can get down to 50.
If you are doing a SLAM, you should check chlorine and raise to slam level a minimum of 3-4 times per day. The more often you can do it, especially the beginning, the better. But no need to check more than every 2 hours.

 

[Newdude]

get a submersible pump (I don't have a backwash option) and try to exchange 25-30% of my water to lower my CYA level to 70. What are your thoughts?

90 has a slam target FC that's 8 more than 70. Once the FC is in the 20s, there's excessive burn off and it will be difficult to maintain the FC target at 90 CYA. Very difficult even.

That said, if you have to buy a pump and pay for water, it may be a wash on the extra chlorine needed. IMO every pool owner should have a submersible pump because they are like shop vacs. You dont really need it until you do, and then it's worth it's weight in gold. I like the 1.6 HP pump on amazon that's $83. It's a beast.

Lastly, how long should I wait to test after each addition of Chlorine?

To verify you reached target, 15 mins with good circulation is plenty. You really only need to do that until you are comfortable with your bleach supplier and pool volume.

*or if you ever see excessive loss to make sure it's loss and not weak bleach.

*or for the evening part of the OCLT test.

 

[Visa1976]

That said, if you have to buy a pump and pay for water, it may be a wash on the extra chlorine needed. IMO every pool owner should have a submersible pump because they are like shop vacs. You dont really need it until you do, and then it's worth it's weight in gold. I like the 1.6 HP pump on amazon that's $83. It's a beast.

Is this the one you are referring to? Amazon Sump Pump

 

[Newdude]

Is this the one you are referring to?

Yup

 

[Visa1976]

Thank you @Newdude and @Parac ! So, I've got the sump pump suggested. Ready to start the exchange, EXCEPT that the sump pump is showing a rate of 9.75 gallons/minute and my hose putting water in the pool is only able to replace water at 7 gallons/minute. Do you have any advice for helping me navigate this? Do I turn pump on and off? Do I try to use an additional hose and hope it doesn't disrupt the water exchange (my normal water input runs through a permanent hose into the shallow skimmer)?

 

[mknauss]

You can use a second hose run to the skimmer.

Or you can run the pump until the level drops a foot or so, then turn it off and let the fill catch up, etc.

 

[Visa1976]

You can use a second hose run to the skimmer.

Or you can run the pump until the level drops a foot or so, then turn it off and let the fill catch up, etc.

Great! Thank you! Either of those suggestions your preferred method? I'm just a Newbie trying to do what I'm told. Also, I'm having trouble figuring out where to drain the pool water. We have no sewer openings on the street near our house. I do have a couple of drains in the concrete around the pool, but it looks like those might drain into the hard - although I am unsure. Thanks for your help!

 

[Newdude]

Also, I'm having trouble figuring out where to drain the pool water.

That's all local practice. Around here most run the hose to the street (with or without drains) and nobody bats an eye. If you have an HOA, there's probably some Karens on the board tho.

Is there a house behind you or only on the sides?


For the flow issue, a 3/4 threaded shut off valve would also work, available anywhere they sell hoses.

Like this one

The house pressure/flow will probably fluctuate over the many hours it will take.

 

[mknauss]

I would run a second hose to the skimmer. Just modulate how much you are putting in with it so things balance enough that you can get some sleep tonight.

If your home is tied to a sewer system you have a clean out somewhere on the outside of your home.

 

[Visa1976]

Thanks. Since I have to leave for work early, I guess at this point I will start the process tomorrow after lunch and then let it run through the evening until I hit the magic number.

 

[mknauss]

How much water do you need to exchange? Be sure to add 20% on top of the absolute number. At 9 gpm, it will take quite a while.

 

[Visa1976]

How much water do you need to exchange? Be sure to add 20% on top of the absolute number. At 9 gpm, it will take quite a while.

With my CYA at 90, I was encouraged to get it down to at least 50 which would require a minimum of 45% replacement on my 15,000 gal salt water pool. I had read to over shoot it about 5-10% which would require an approximate 14hr discharge at 9.75gpm (sump pump speed). Does that math sound correct to you? Should I replace more?

 

[wireform]

Yes, 55% of the pool water to be exchanged will include the extra 10% water exchange which is 14 hours.

 

[Visa1976]

Yes, 55% of the pool water to be exchanged will include the extra 10% water exchange which is 14 hours.

Thank you! Calculations are changed after just starting. After hooking up the three hoses it took to get a line run from the sump pump to my sewer clean out (only way not to incur the wrath of HOA Karens) - it appears my sump pump is spitting out water at a rate of 25 seconds per gallon, or 2.4 gpm. Which such a reduced rate: going from 90 CYA to at least 50 CYA @ 15,000g pool, I need to exchange 55% of the water including buffer amount which comes out to exchanging 8,250gallons of water. At 2.4gpm from sump pump, it will take me 57:20 or 2 days, 9 hours, and 20 minutes. Anyone willing to check my math and have any advice for speeding up the process?

 

[mknauss]

Get bigger hoses. It will not be efficient at that rate. You would be better off to rent a large size sump pump with hoses and drain it quick and refill. Start in the afternoon and fill over night.

 

[Visa1976]

Get bigger hoses. It will not be efficient at that rate. You would be better off to rent a large size sump pump with hoses and drain it quick and refill. Start in the afternoon and fill over night.

Alright, so I brought it down to just one hose and opted for a different drainage area, now my numbers are going from 90 CYA to at least 50 CYA @ 15,000g pool, I need to exchange 55% of the water including buffer amount which comes out to exchanging 8,250 gallons of water. At 8.96 gpm from sump pump, it will take me 15.5hours to be on the safe side. Is that fast enough?