Hi, I have a 400 gallon 8' tank with 3 13" tube lights over the top. This was a test as I couldn't speak with anyone that had good knowledge of how to do this. I started with 1 in the middle and liked it so added 2 more evenly spaced. If I did it again I would use the newer 24" Pipes 1' apart. The light would be unbelievable.
You want to make sure that the tubes come down to the top of the tank but brake near ceiling so you can take lower half off of the tank for cleaning. This is done by hanging original pipe down thru ceiling about a 1' or more and then having a separate tube that you push up onto the other tube so that you can effective clean but get the most light to the surface of the water when not cleaning.
The company that I went with was a great deal of help (Sunpipe) but went out of business. It appears that an overseas company is now called Sunpipe. Most solatubes have UV resistant lenses on the roof. You should check to see if you can get a different type of material that doesn't take all UV light out as this is good for your aquarium. They make them this way because they don't want interior fading in houses. There are other companies that make similar products. The ones I purchased were used very successfully in the Chicago zoo as they wanted UV light. I'm on the East Coast of Central Florida. They worked very well. I did need to supplement my lighting with some LED blue and white strip lights. This helped set the color off of the fish and corals and also allowed for better night time viewing such as when the time changes early evening. I used these
https://www.marinedepot.com/Current...quariums-Current_USA-CU03002-FILTFILD-vi.html
I was told when getting my solatube type lights that the colors would be off. They are off from normal aquarium actinic lights. Interesting as on rainy days its darker. When clouds move by the light shifts. Some full moon cloudless nights I actually had moon light lighting the tank. It even provided shimmer on the water at times with proper water movement at the surface. I used to have a chart that showed the wattage comparison for the different size tubes.
If I was in your situation I would purchase and install myself. It is not hard to install these. Find the center where you want it and trace a hole mine came with diagram. Use jigsaw or saw zall cut out hole and install using good roof caulking. I would absolutely choose the largest size you can afford. They make them for industrial buildings up to 24" diameter. I had 13" diameter on my tank. Depending how long your tank is I would try to space 1' apart. Do put a lens on the bottom of the tubes that is the proper material not to block the UV. You may have to purchase the material from a local plastic shop. If you leave open humidity builds up in the tube and drips back down causing tube finish to degrade. I tried that in the beginning. I'd be happy to speak with you or show you a picture of my tank. I've recently taken the lower part of my tubes off and placed normal domes on the ceiling as I was trying to sell my home and people felt the exposed tubes were a bit industrial like and they didn't know how to fix so I fixed them to be more normal to sell. I have a picture showing the tubes and also the extensions and the aquarium.
Several ideas to think about. They are now making night time solar powered lights that mount inside the tube. If you could get the correct spectrum bulbs this would be interesting for night time viewing as it reflects off the inside of the tubes. Each size tube has a different wattage at high noon. In the beginning I believe I found out that the 24" tubes provide 1000 watts of light. I also found out that the length of the tube makes a difference. The longer the tube up to like 13' actually provides more light but as it get shorter less light and longer then 13' less light. You might want to check this. The company that I went with that went out of business actually made a curb out of metal that housed any number of tubes you were going to install. It was a neat concept. So on the roof there was going to be a metal box that each tube passed thru to hold them in place. I've even seen people that have the tubes stick up above the roof so as to get more light from different angles due to the pitch of the roof. Mine stick up about 2' and have made it thru 4 hurricanes 0 problems. I've also seen in recent years someone is building a new prism style top on top of the pipe that is supposed to produce more light. One other thing to consider is there is no heat transfer to the water. This is a very good thing as you know.
You can email me thru this site and I will share the pics with you.
