[Jet cleaning, removal, repair]

If you are facing the problem for a long time...why did you not call a professional contractor? I think they can tackle you from this situation.

[New Air blower in swim spa won't turn off]

I think the power button of the air blower must need to be changed or repaired, i have had the same issue but i got it fixed after service of the blower.

[Homemade In-ground Pool Heater?]

It doesn't seem like there are any tutorials or resources available to build DIY inground pool heaters and there are way many tutorials available on above ground DIY solar pool heaters costing 100$ to 200$. If you found something let us know as well.

[Robotic pool cleaner]

Sadly, a lot of old style pool cleaners are still in use, and few are still available in market. These can consume sometimes over 1,000 watts – which cost a LOT more in expenses to operate as compared to newer, low-voltage units. 

You can search for latest energy efficient pool cleaners in market but make sure you do also some research on clients reviews and find few genuine reviews before finally selecting the one.

[Weeping tile]

I think it would cause some problem for you, you need to install a good drainage system other wise their would be a problem for you, If you can attach some pictures then it would be good.