I have had a 58 gal with open top for the last two years. I am in the process of selling it and setting up a 120 gal the same way. Should have the 120 up and running by the end of this month. Just waiting on the carpenter to finish the custom stand.
I have been buying equipment and supplies piece-meal for the last 10 months for this tank as I had $$ available:
- 100% Onyx Sand for substrate
- Gas CO2, Tom Barr reactor(from when he was making and selling them earlier this year)
- Two 175w Metal Halide pendents with electronic ballasts for lighting from Champion Lighting
- A DIY wet-dry (as per Tom Barr's plans and suggestion) out of rubbermaid trash cans and containers, and using an Amiracle overflow prefilter. I had a wet-dry on a 125 gallon tank about 10 years ago and it worked great - no surface scum, no concern about adding additional fish to the tank. Back then it did cause me to run CO2 at a slightly higher level, but CO2 is cheap. With my new design I don't expect CO2 usage to be that much more significant with my wet-dry over the use of a canister.
I may add a 6 inch "rim" around the top, matching the oak stand, to cut down on the light spillage and glare into the room from the MH lighting, don't know about that yet.
From running open top on my 58, yes I lose about an inch of water per week in the winter when the heat is running. Plant tanks with CO2 and lighting are high maintenance anyway, so its not like alot of extra work to top off the tank. I notice no rise in humidity in the room, or mold on windows, etc, like reported in your link. The extra humidity (if there is any) would actually be a plus in the winter. Yes you do have to avoid jumping fish, that just goes with the territory and is not a big deal for me. The rim, if I go with it, though, would probably aid considerably on this.