I installed them on both my tanks. I put the strips on the holding tank but I used the probe in the fresh water tank to avoid taking out the tank or cabinets. I drilled a hole in the cap on the water tank to insert the probe and used a trailer light plug to connect the wires so I can easily remove the cap and probe. Installing the strips on the holding tank was fairly easy. That is if you can imagine that installing anything in a tight space easy for someone 6'5.
The two monitors are installed on the nav station. Would like to say I am happy with them but they need to be reset to often and the very small little set buttons are hard to use and can get damaged pretty easy. Direction were a bit confusing and I know several people that had to SCAD for help. If you want pictures I can take them next weekend.
If you use two monitors like I did, I suggest you label them immediately so you remember which tank they are for. Don't laugh because you will forget by next season!