Newbie - chemicals query

[smashed]

Hi, I recently just bought a used hot tub and am trying to research a few things to ensure that I don’t end up ill. The tub had not been used in a couple of years. I did read the guides but I couldn’t find anything on chemicals.

I did a quick fill and partial empty via the valve. I then tried to empty the rest but for some reason no more water came out. I resorted to removing the water from inside the tub but that then leads me to worry about any water left in the pipes...
What is the best way  to fully remove all the water? I did read that I could undo some plumbing but I am a little weary that I will just create a future leak.

I plan to use a flushing product to clear the biofilm but I obviously then wish to fully empty the tank..see above.

Although AquaGarde / AquaFinesse looks great it is also expensive. I am therefore planning on resorting to Bromine. The previous owner has given me a tub of bromine but most of the tablets seem to have broken down. I assume that I should discard this and buy new bromine tablets?

Aside from that, is it just a case of testing the water levels on a daily basis with a testing kit?

Thanks for any help in advance.

[Jacuzzi Jim]

 Prolly to late but yo9u can just suck it out with a wet/dry vac if you have one, if not just bail as much as you can out.    Refill it and nuke it with chlorine or even a gallon of liquid bleach,run for a day then drain.  Best case get a btl of swirl away or jet clean and follow the instructions.

 Chem wish I like chlorine the best once or twice a week shock once a week.    Bromine is ok with lots of use but it varies and smells like chlorine. 

[smashed]

Thanks - I have just sited the tub and was about to give it a decent nuke.
However, I just noticed a number of small blisters on the shell. They are in the footwell, base of seats and are probably about an inch in diameter but none are hugely pronounced. I only noted them because I ran my hands over the whole shell to check for them.

They are all hard and none appear to have cracked. Should I leave them whilst they are no trouble or should I be trying to heat, prick and reseal? I dont want them to fail and all start leaking but then I dont want to puncture holes and then cause just as many problems myself.

It is acrylic with a fibreglass undershell.

Thanks