I have a Spa that's from 2004 originally... We picked it up second hand for a steal.

It's been worked on and is in fairly good condition, It works after all.
However the Electric heating is quite expensive and I need to fix a couple of the jets... Since I'm going to be changing the heater and jets.. I was wondering how it goes putting in valves for some of the jets...
There's 6 big jets and then there's 8 tiny jets, I'd like to put in a valve to turn off the smaller jets to have just the big ones.
and I'd like to replace the stock controller, It turns on unexpectantly when in the off setting, So either it's buggered or it just really likes to be on.

So I'll be arduino controlling the spa, Temp and Flow sensors throughout, with a portable Gas Hotwater system, Also arduino controlled.
All that is easy.

I just want to know if putting valves on different sets of jets is a good idea. Will that cause pressure issues If I leave the 6 big jets always connected.

I'll draw a diagram of the setup if someone needs