Can you post some photos of your diseased anubias? What makes you think it has a disease rather than another issue?
If they do have the anubias disease then emersed or submersed the plants will die and the only way to stop it from spreading is to cut off affected areas and clean your blade between cuts so you don't spread it the new plants. Do not let the infected plants touch uninfected areas of other plants.
I wrote a sticky note a few years ago on how to set up an emersed tub which can grow all kinds of aquatic plants: http://www.aquaticplantcentral.com/...inners-guide-starting-your-first-emersed.html
I'd use soil rather than clay and mister. That way your plants don't run the risk of fertilizer burns if you are adding too much ferts to the mister. You cannot use concentrated fertilizers when misting, you'd need to use an extremely - extremely - dilute fertilizer solution if you apply it directly to the leaves.
Too much water on the leaves will cause them to rot. Your plant leaves should not be constantly wet. The humidity level will be correct if you follow the guide above. Keep in mind you'll probably lose some leaves when you pull the anubias (or any submersed plant) out of the water. This is because submersed leaves lack a wax cuticle and cannot prevent themselves from drying out. The plant must convert and grow new emersed leaves (which conversely block nutrient uptake and gas exchange when placed underwater).
I've personally never misted my plants. I allow them to lose their submersed leaves, then let them grow out emersed leaves which are adapted to emersed conditions. If you are trying to keep the submersed anubias leaves then 2x a day to begin with will probably be enough. Just make sure the leaves don't have sopping wet puddles on them the entire day. Just mist them enough to prevent the leaves from withering and drying out. They'll likely die eventually anyway so it may not be worth it to go through all the effort of misting them.
Since you don't have to worry about algae or running out of nutrients with a soil substrate you can blast the light as intensely as you want without issues. Also, keeping extremely long photo periods won't cause harm (and in fact will likely give the plant more time to gather energy and grow). So a 12-14 hr light cycle would be fine. Keep the bulb as close to the plants as possible without burning them.
If they do have the anubias disease then emersed or submersed the plants will die and the only way to stop it from spreading is to cut off affected areas and clean your blade between cuts so you don't spread it the new plants. Do not let the infected plants touch uninfected areas of other plants.
I wrote a sticky note a few years ago on how to set up an emersed tub which can grow all kinds of aquatic plants: http://www.aquaticplantcentral.com/...inners-guide-starting-your-first-emersed.html
I'd use soil rather than clay and mister. That way your plants don't run the risk of fertilizer burns if you are adding too much ferts to the mister. You cannot use concentrated fertilizers when misting, you'd need to use an extremely - extremely - dilute fertilizer solution if you apply it directly to the leaves.
Too much water on the leaves will cause them to rot. Your plant leaves should not be constantly wet. The humidity level will be correct if you follow the guide above. Keep in mind you'll probably lose some leaves when you pull the anubias (or any submersed plant) out of the water. This is because submersed leaves lack a wax cuticle and cannot prevent themselves from drying out. The plant must convert and grow new emersed leaves (which conversely block nutrient uptake and gas exchange when placed underwater).
I've personally never misted my plants. I allow them to lose their submersed leaves, then let them grow out emersed leaves which are adapted to emersed conditions. If you are trying to keep the submersed anubias leaves then 2x a day to begin with will probably be enough. Just make sure the leaves don't have sopping wet puddles on them the entire day. Just mist them enough to prevent the leaves from withering and drying out. They'll likely die eventually anyway so it may not be worth it to go through all the effort of misting them.
Since you don't have to worry about algae or running out of nutrients with a soil substrate you can blast the light as intensely as you want without issues. Also, keeping extremely long photo periods won't cause harm (and in fact will likely give the plant more time to gather energy and grow). So a 12-14 hr light cycle would be fine. Keep the bulb as close to the plants as possible without burning them.
