Why Can't I get My TA down- AND stay there?

[MelissaEly]

Problem: Chronic high TA despite massive amounts of muriatic acid and continuous algae growth
FC: N/A - we have a Simple Salt System
TC: N/A - we have a Simple Salt System
Simple Salt System set at 3.
pH: <7 right now (I ran out of pH increase)
TA: anywhere from 100 - 180+ ppm (this morning is was about 180 ppm)
CH: 328 ppm
CYA: 15 ppm (as of last Saturday- stabilizer added)
TDS: 1300 ppm (important measurement for Simple Salt system to determine if Calcium is needed)

My pool: above ground, 28' round
Pool chemicals: Simple Salt system, no chlorine, no salt tablets (routine, may need to add salt at the beginning of the season; did not need salt this year).
My pump & filter: cartridge filter
Other info: water temp fluctuates (thank you Ohio!) between 80 - 90 most days. Light bather load. Lucky to not be near trees.

My TA is chronically high and I fight algae CONSTANTLY. Spoke with our pool company about it and he recommended keeping my TA around 90 ppm and to use muriatic acid (instead of ph Decrease, which I had been using) to lower it and treat the pH separately. And, of course, this should keep the algae from growing. My pool is crystal clear (only about 3rd time this Summer), but I can't keep TA below 100. Finally got there yesterday, only for it to be at 180 this morning. I go through several gallons of acid a week. AND- there's algae growth on the bottom!!! Again! I've vacuumed it about every night this week to keep it at bay, to no avail. I just can't keep the algae from returning.

We have been under drought conditions, and I have added water (and our water is notoriously hard), although not weekly. It has been quite dry here, but we have gotten rain 2 days this week.

I thought to myself today (as I was putting in the pool vacuum...), I have a love/hate relationship with my pool. I love floating around to relax and watching my daughter have fun, but I hate that I cannot figure out how to get the chemistry near proper levels without spending the money we keep spending. I've sent my husband to the pool supply store for more acid, algaecide, and pH increase...

[Teapot]

FC: N/A is NOT true, you still have to measure it or you are pissing in the wind. even a simple salt sytem will produce chlorine from the salt using electricty passed through the cell.
If your water supply is TA 100-180 your pH will rise with aeration and TA isn't really a concern in a vinyl pool provided your pH is reasonably stable. Salt cholrinators produce some aeration so usually suffer from rising pH, sounds like you are?
You can't just add muratic, you add muratic and aerate to raise the pH but leave the TA where it went down to after adding the muratic acid. you repeat this process until the TA is where you want it to be 60-100ppm ish. Don't waste your money in pool stores, stick to grocery stores! Chlorine bleach, Muratic acid is about all you need and a decent test kit not strips.
TA has zero to do with algae, chlorine has 100% to do with killing algae.

[Denniswiseman]

Your salt system probably isn't producing sufficient chlorine to kill your algae. You will need to add some additional chlorine
With a SWCG (salt water chlorine generator) you really need a CYA of 70 with a target of 5 for chlorine and a shock level of 28
Use these common products to balance your pool
Liquid chlorine (sodium hypochlorite or plain bleach)
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Soda ash will raise pH and TA