We've just bought an Artesian South Sea Spa (1200 litres). We had it 4 weeks and found lots of foam and bubbles and learnt that this was from people's deodorants and hair conditioner etc so I re-filled the hot tub 4 days ago. I refilled it and noone has been in it as I wanted to get the chemistry right. We live in a very hard water area. We were given some test sticks (https://www.aquachek.com/aquachek-chlorine-4-in-1/) from the company we bought it off (should I be using something better) and it's now reporting the chlorine level is fine but ph(7.8-8.4) and alkalinity is high(180-240ppm). I