Cloudy hot tub

[Eddles]

Problem:

My parents have a swimming pool and hot tub over 15 years old. My dad recently developed dementia and was doing chemicals wrong, so I've taken over responsibility for the pool but I'm a bit out of my depth and my dad is no help really, he's quite confused.

We've had issues with cloudy water in both the pool and hot tub. I've fixed the pool, somehow. The hot tub was a huge problem, the water pretty much looks like milk. Changing the water was fine for one day then milk again. Eventually, I got the original installers to come over and train me on how to look after it. The day after, the water was sparkling crystal clear, and I was happy. It had its first ever service a couple days later. A few weeks later, the water suddenly turned cloudy again and I don't know how to fix it. Frustrating. Here's a picture of the tub 3 days ago on 10th June - it's slightly better now, but I'm hoping you guys can help me please. I think it's a 1200 litre hot tub, not sure what other details are needed. I'm happy with the measurements apart from low FC. I've tried Oxyshock but no change - I put in 56g Oxyshock the day before the picture was taken (9th June).

Today, the measurements are:

FC: 0.5
TC: 1.0
pH: 7.5
TA: 90
CH: 380
CYA: <30

My pool: 1,200 litre indoor hot tub, don't know anything else.
Pool chemicals: Chlorine granules, Sodium Carbonate pH increaser, Sodium Bisulphate pH reducer, Oxyshock, and others.
My pump & filter: Not a clue. I do know it has 2 Darlly filters.
Other info: ?

I'd really appreciate any advice!

[Teapot]

Please post only once on a topic, it's confusing otherwise.
Oxyshock isn't chlorine so it won't increase the free chlorine level. Oxyshock is peroxymonopersulphate, it will show up on tests as combined chlorine.
How come your TA is much lower in the hot tub when presumably it's the same fill water as the pool?

[Eddles]

Sorry, it's just that it's two different problems in two different pools.

I presume the TA in the hot tub is lower as it has jets & bubbles, so that has the effect of increasing the pH without affecting TA. I always have to put in pH reducer in the hot tub quite often to bring down the pH, which I presume brings down TA as well. I've never used pH reducer in the pool, it slowly drops over time, so I have to use pH increaser which increases TA as well. I'm fine with the chemicals in the hot tub, I just don't know why it's cloudy.

The hot tub guy that visited recommended using oxyshock in the hot tub once a week along with chlorine granules as it won't cause chlorine to shoot up too high?