What's the recommended TA for a hard fill water pool? Also battling some old scale

[FirstVallartaPool]

My numbers are currentlyTc 5
Fc 4.5
CC .5
Ta 40
Ph 6.8-7.2
Cya 62
Ch 500


Scale build up on this 10 yearold pool is also what I'm dealing with. Not too bad now its just above water line and I got it all off with 220 wet sandpaper.
A member posted this advice Re scale
"To avoid it in the future maintain your CSI slightly negative, -0.1 to -0.3. I had issues with scale on the waterline tile a couple of years ago and it hasn't been back since. Enter all your numbers in Poolmath and it will give you a CSI score. Tweak PH, TA and CH to adjust it. If your PH tends to rise then keep your TA lower (60-80) to help slow the rise. "
Also water quality is almost clear crystal but not 100% I plan on deep cleaning the sand filter and if that doesn't do it then researching here about fading DE to it?
Thanks again!

 

[Texas Splash]

You may be keeping the TA and pH low to compensate for the elevated CH, but you're a bit too low. The CH of 500 will be fine if you keep the TA around 50-60 and pH around 7.5-7.6 or so. No need to drop too low on TA and pH. Just keep an eye on those CSI numbers on the Poolmath Calculator.

Watch your FC though. It's too low right now. Target FC for a pool with CYA of 60 is about 7, never below 5. Hope that helps.

 

[FirstVallartaPool]

Ok. Just retested all 7 and here's where at now. Btw We've been getting a fair bit of rain [including last night] as it is the rainy season here.

Fc 2.5 to 3
Cc .5
Ta 45
Ch 275 to 300
Cya 80
Cl 4.5
Ph 7

Thanks again as I need all the help I can get. I have 2 more weeks to get this water under control then I have to fly out for a couple of months leaving the basics to my friend.. this is all new to me!

 

[pooldv]

Ph is a bit too low, it needs to be between 7.2 and 7.8. Rain will usually raise PH a bit through aeration. As Pat said, aim for TA between 50 and 60. Raise it to 50 with baking soda.

More here on pool chems, Pool School - Recommended Pool Chemicals

 

[Schadenfreude]

Your FC is far too low for your CYA level. Are you chlorinating with dichlor or trichlor? Those both have CYA in them. Your CYA is too high for a non-SWG pool.

 

[FirstVallartaPool]

Im not sure what the chlorine powder is..it is in a large 20kilo tub..the pro pool services here use it so dont know if is di or tri [guessing tri as there has never been any cya conditioner added that I am aware of to pool]..is there any way to test it? Re cya level is 80 so high i need to empty the pool or half , before attempting raising ta with baking soda or anything else? Also forgot to mention a good half cup of acida was added a couple weeks ago to lower ph as the Ph was too high [which has usually been the issue, not too low like now]
Would you guys help me with specific plan of attack now with these numbers as i really know very little at this point. I'm trying to learn fast. This is obviously not a perfect situation but last option is hiring a pool service that will do basically the same thing. I need to sort out then get a system in place for my friend to manage.
Very much appreciated as I feel very much overwhelmed right now

 

[pooldv]

Do you have access to bleach or liquid chlorine? It would be best to switch to a liquid source for chlorine because it doesn't contain CYA.

 

[FirstVallartaPool]

Not really here. Its the industrial powder chlorine unless I lived here full time and could add liquid bleach daily from the supermarket etc. I'm aware the cya component and hoping I can get some help from the forum for a system that's practical. Or else it's back to a pool service that uses the same powdered chlorine. Anyone here that can help as what to do now with these latest results would really be appreciated. SOS!

 

[pooldv]

How about this?

Keep TA between 50 and 60
Keep PH between 7.2 and 7.8
Keep FC at target for your CYA, [FC/CYA][/FC/CYA]

Once CYA reaches 80 you should drain 50% of the water to lower CYA to 40.

 

[FirstVallartaPool]

OK thank-you. I will drain half the pool and start again to get to fc 3 to 5 [I assume I do this by adding the tri chlorine powder till I test that number?]
I understand liquid bleach containers no cya raising conditioners but so far I have not figured how to practically make that work in this location. This pool situation is still a work in progress.

 

[pooldv]

You can use PoolMath to calculate how much trichlor to add to get your FC TO 5 ppm. There is a link at the top of each page. Here is how to use it, Pool School - PoolMath

 

[FirstVallartaPool]

Ok many thanks to you and everyone as I really feel like a newbie out of water. Im draing half now as we speak. Luckily it is a small pool.

OK just did cya test now after draining half the pool 38-40 yay! Doing rest of tests now waiting for chlorine to dissolve ..
OK new results in...any insight as to what to do next? Water is not super clear like it has been last year but not terrible.
Ph 7.2
Ch 175
Fc 9.5
CC .5
Tc 10
Cya 38-40 yay