Hello, I wanted to share my solution to getting rid of that nasty condensation inside the electronics enclosure that builds up on the dome cap. I live in west coast of Florida and its really really humid here and I’m on the water which makes it worse. So I had to come up with an easy and practical way to get rid of all that damm humidity.
First and foremost make sure the inside of the dome is cleaned. I cleaned it like I clean my telescopes main mirrors with with 60% isopropyl alcohol aka rubbing alcohol and distilled water and use cotton swabs since it wont scratch the dome that will remove any oil that will cause dew to form.
Then use anti-fog spray on the inside and use a lint free cloth. I used two applications.
Then the fun part. I powered up my ROV since the rasberry pi runs warm I wanted to heat the air inside and then I put 20mg of silica packs inside the electronics and closed the acrylic from the back and left the dome off and I installed the vent plug. I also put the dome cap on but barely on so the orings would not engage the housing and went and grabbed a beer and waited a while until the enclosure got warm ( about 15 minutes)
Go to the dollar store and get some ballons. I happen to be a diver and I have several dive tanks filled and ready to go. An interesting side note (Dive air is desicated and humidity is at 67pmm which is pretty dry so it will not rust the inside of tanks… keep that in mind). Fill one of the balloons with the dive air. I like Nitrox so I used the 32% tank. Then I used the nice plastic vinyl tube that Rusty sent with the ROV and the vent adapter and connected it to the ROV and the other end to the balloon and let the ballon fill the enclosure and just barely allowed the air to escape from the dome. When the balloon was empty I quickly pushed the dome into place and replaced the vent plug.
Then I did a vacuum test and filled another balloon. After my ROV passed the vacuum test I used once again the nice vinyl tube that Rusty send with ROV and connected it to the vacuum pumps port to replace the air that was vacuumed out therefore I replaced the removed air with more dry tank air. and then quickly closed the vent plug.
Tested the ROV for hours after that and not a sign of moisture on the dome cap and now my ROV is moisture free and Nitrox certified 32%