Phrags in H/ponics

[taipan]

I have 3 plants of Phrag.pearcei which are standing ( above the rim of the pot ) in water. They look ok & have since I got them about 3 years ago. If all goes well I will be adding some more "water loving " Phrags at the end of the year
I plan to move them to a full hydroponic set up & will most likely have water moving continually.Before people answer ( hopefullly someone will ) please take into consideration the following
In BKK the min.day temp would be mid to high 20's ( deg C ) Max.mid 30's deg C. The coldest it gets would be about 15 or 16 for a few hours before the sun rises - in December. Also the trough will be under shade cloth & open to the elements eg rain wind etc & in the coolest part that I can find
My questions are:-
1) Would there be a greater chance of evaporation taking place if the level of water in the trough was kept at half way up the pot.
2) Should I run the water to the level of the rim to stop the top portion of LECA from dying out too much
3) Should I run the water continually or have the pump set on a timer for running eg once every hour for say 10 to 15 minutes.
4)Would the placement of small pebbles on top of the Hydroton ( cant get Prime Agra in Thailand ) be of any help.
Any other info would be appreciated

[Ray]

1. You'd be best NOT to do full hydroponics, as the common liquid nutrient bath is the perfect way to spread plant pathogens. That said...
2. Evaporation is related - in this case - to surface area. Depth is of no consequence.
3. Pebble on top would be of no value, and temporary besides (they work their way down into the medium over time).

[taipan]

Thanks for the feedback. Based on this I may have to rethink my ideas. Another problem is that the pH of the water is around 9+. That is why I was going to grow them separately & buy containers of bottled water - pH just over 8.