Newbie with a few questions

[salinity]

Hi all - newbie here - just bought a house with an aged but functioning above-ground pool system (despite my user name it is NOT a salt system). Opened it up this weekend and trying to get it dialed in with the help of TFP. I had to get a new pump, so I downgraded to a 1.0hp from 1.5 hp that was previously installed - crunched the turnover numbers and it seems 1.0hp is fine for my size pool, plus it allows me to try out a simple plug-in timer that's rated up to 1.0 hp.

I took some initial measurements this weekend - pH was high (8.2 or so) so I worked to get that down to about 7.5ish then started adding liquid chlorine. Pool looks ok - some brushable brown stuff on the bottom (algae?) that doesn't come off completely with brushing that I hope to work on, some staining on the vinyl liner bottom and sides, but no green and the water is mostly clear for now. I ran the pump overnight last night to circulate the added chlorine and turnover the water 4+ times, but plan to do 12 on 12 off. Here are my current numbers (via the TF-100):

FC: 5.0
CC: 0.5
TC: 5.5
pH: 7.5
TA: 100
CH: 40
CYA: 0

Questions:

1. Obviously I need to get the CYA up, but I want to vacuum, backwash the filter, etc (hopefully today) before I add it - is this a logical line of thinking? The stabilizer I have says add to skimmer and don't vacuum or backwash for 3 days.

2. Is there any reason to raise the FC levels up higher? Could the stuff I'm brushing on the bottom be signs of a potential algae problem (it's mostly on the bottom), or it this maybe leftover stuff from the pool being closed?

3. I noticed some bleached out spots on my liner on the bottom, likely where the PO was adding chlorine (its under the return flow). One spot (prob 2 foot diameter) feels like it's hard and looks like its shriveling, though its not leaking water that I can tell. Other than being careful to slowly add and try to disperse the chlorine, should I be overly concerned? I can't find any other accounts of "hard spots" on a vinyl liner floor. I was thinking if I can find a large pad to put over it (think large ladder pad), that might be good.

Any other advice or info is greatly appreciated!

 

[mknauss]

Welcome to the forum!

Turnover is not a significant issue in pools. Most people drastically over circulate their pools. Read Pool School - Determine Pump Run Time
Do the bulk of your vac to waste, etc. prior to adding CYA. We recommend adding CYA by placing the powder in a sock (tube sock, knee high nylon), tie it shut, and hang it in front of the return flow from the pump. Or you can put the sock in the skimmer as long as it does not restrict water flow. If put in the skimmer you should run your pump until fully dissolved. By doing it this way, the CYA will be in the system and you can test for it within 24 hours after it is dissolved. You will be able to backwash and not lose a significant amount.

You need to SLAM Process. Once you have added the CYA and tested your pH and adjusted to 7.2 with muriatic acid, you raise your FC to SLAM level based on [FC/CYA][/FC/CYA]. You MUST have a FAS-DPD test to measure the FC. What test kit are you using.

Sounds like solid chlorine (cal hypo and/or dichlor) was used in the past and sat on the liner. It is also possible acid was added and was let to pool in one spot and that has damaged your liner. It may need to be replaced in the not too distant future.

Always add liquid chemicals directly to the return flow of water into the pool. Use a brush to mix up the area.

There is a start. Post back here with questions or comments.

Take care.

 

[salinity]

We recommend adding CYA by placing the powder in a sock (tube sock, knee high nylon), tie it shut, and hang it in front of the return flow from the pump.

Thanks for the tip - How long might it take to dissolve with the sock method if I'm raising from CYA <20 (hours, days)?

You MUST have a FAS-DPD test to measure the FC. What test kit are you using.

I have the TF-100

Sounds like solid chlorine (cal hypo and/or dichlor) was used in the past and sat on the liner. It is also possible acid was added and was let to pool in one spot and that has damaged your liner. It may need to be replaced in the not too distant future.

Roger that - are there large sinking "pads" available (similar to a ladder pad) that I could put over the spot to reduce the wear / extend the life? I haven't found any yet.

I'm a bit curious about shock FC levels and "safe" swimming FC levels. The shock chlorine I have (12.8% I think) states to raise FC to 7 and I've read that you shouldn't enter a pool with FC > 5. Is this simply not true? (the linked chart shows shock FC 12-24 with appropriate CYA and swimming levels up to 9 (almost double the recommended safe swimming level). Does the CYA level influence what impact the chlorine has on human skin, eyes, etc?

 

[Texas Splash]

Marty's off-line at the moment, so I'll help with a couple items:

How long might it take to dissolve with the sock method if I'm raising from CYA <20 (hours, days)?

Once the granules are soaked in a sock, you can have them all "squeezed-out" in a matter of an hour or two if you stay on it and squeeze a lot.

I'm a bit curious about shock FC levels and "safe" swimming FC levels. The shock chlorine I have (12.8% I think) states to raise FC to 7 and I've read that you shouldn't enter a pool with FC > 5. Is this simply not true? (the linked chart shows shock FC 12-24 with appropriate CYA and swimming levels up to 9 (almost double the recommended safe swimming level). Does the CYA level influence what impact the chlorine has on human skin, eyes, etc?

That is old antiquated pool industry talk. As long as you reference the [FC/CYA][/FC/CYA] and don't exceed the FC level for your current CYA, the water is safe to be in. The CYA buffers the harshness of the chlorine. The higher the CYA, the higher the FC - they go together.

 

[salinity]

So I vacuumed, brushed and backwashed the filter yesterday, then worked to get my CYA up. I added some chlorine and did a test before bed (then added another sock of CYA) and again around 9am this morning - here are the #s (am test on right):

FC: 5.5. 5.5
CC: 0.5. 0
TC: 6.0. 5.5
pH: 7.4. 7.4. (Between 7.2-7.5)
TH: 40 40
TA: 90 90
CYA: 20 40

I added a touch more ALK raise (target 5-10ppm increase). I won’t be able to do the bed test / re-test in the am for a few days, but can stop by to add chlorine and do a one-off test (we’re officially moving in on Sunday). Now that my CYA is up, should I get my chlorine up to shock level, or because I lost so little overnight, just work to maintain the 5-6ppm level for the time being? The pool looks great for what it’s worth (knock on wood).