@everybody who loves to see it even bigger and deeper,
Regretably I'm not too interested in making the pond any deeper than 70-75 cm due to many reasons and I've had think it over and over. The deeper you make (just say more than 1,25 m), the more serious the equipment must be and that will translate to high end tech with high running cost. You will need very serious pumping power (something like 2/3 hp pump), extra powerful metal halides (probably 2-3 of those 1000W ones), freakin huge chiller (probably 2-3hp AC machine) and all kind of very serious power machines. Maintenance will also be a PITA not to mention the monthly power bill. Another factor is building cost. Keep in mind that this is a project done along with the whole house.. think of fund availability should I make something of monstorous (something like tom barr's creation scale) proportion. Much more serious bracings and concrete blocks will be needed and not to mention those special built glass planks which may cost you a leg.
For something that is built permanently right inside a living room, it will run for as long as the house stand which might be decades before the next renovation (that is except in the future minor modifications are made on the garden) unlike of a huge glass tank. Think of if more like an inwall tank with 1 side of glass, which is a permanent feature and requires someone who is willing to spend time or fund (to hire caretaker) to maintain it. So making it easy to maintain and low running cost is the key, more like your lawn garden which last indefinately.
1. House walls (painted)
2. Garden walls (textured, built on and planted)
3. Opening with clear polycarbonate roofing
One of the helping factor is free, quality sunlight. The space used to be a terrarium garden as I have already told you so. There is a huge opening by the top and if I'm right it measures around 2,5 x 2,75 meter. To keep things more humid and prevent pollution (rain water, dust) from coming in, this time I will add clear glass-like polycarbonate roofing (japan's SunLoid) which is usually used in greenhouses.
If we see this picture above which is taken at around 3pm, it is very clear that sunlight penetrate and falls to the lower part without any problem. The garden/pond area is directly hit by strong sunlight for several hours, that is around 11am to 2pm. The opening slightly face west and the garden recieve more light from late morning to early evening.
The fact that plants like pothos and creeping phylodendrons used to live very thickly from top to bottom is a proof that I have enough natural light for the pond but probably just by medium level when it reach the bottom. So the plan is to supplement using metal halide lamp, either a single 1000W fixture or twin 400W and hang it at certain height so it lights up the undergrowth/pond. Just 2-3 hours a day would be more than enough and it does not hurt bad on the bill (less than 2-3 hours worth of air conditioning for my bedroom). Even with careful plant management I can totally eliminate the need of MH, but it hurts on the beauty aspect (no viewing light and no cool ripples).
*just to let know that this is not a mere plan. This is a project in construction. Comments are valuable and inputs are highly welcome as consideration and vital addition.