Ai hydra 32hd or prime 16hd?

NeptuneRjo · Apr 7, 2020

For a mixed reef in a 20w by 24h tank, which light is better? It seems the 16hd doesn't have the best penetrating power but the 32hd is a little overkill. Any recommendations? I'm leaning towards the 32.

lpsouth1978 · Apr 7, 2020

What are you keeping in the tank? If softies and LPS, and some SPS in the center, I would go with the 32. If you would llike to keep SPS throughout, I would actually go with 2 16's. This would allow you to spread them out a bit more to cover the whole tank. It would be the same amount of light as the 32 with better coverage.

NeptuneRjo · Apr 7, 2020

lpsouth1978 said:
What are you keeping in the tank? If softies and LPS, and some SPS in the center, I would go with the 32. If you would llike to keep SPS throughout, I would actually go with 2 16's. This would allow you to spread them out a bit more to cover the whole tank. It would be the same amount of light as the 32 with better coverage.

I'm going for sps and Lps mixed throughout with some softies (zoa's and such) around the bottom. I'll look into 2 16s thanks

NeptuneRjo · Apr 7, 2020

Would there actually be a difference in spread in a 20"w tank?

lpsouth1978 · Apr 7, 2020

NeptuneRjo said:
Would there actually be a difference in spread in a 20"w tank?

IME, absolutely. The Hydra 32 will have a definite funnel where the light on the edges of the tank will have VERY low PAR. By using 2 16, you will be able to separate the pucks by ~6 inches more, evening out the coverage and getting good par across the entire tank. Even just a few inches extra spread will make a big difference.

I feel that the manufacturer overstates the footprint their lights will cover. BRS has done some testing on the Primes (the 16's will be very similar) and concluded that they are not really sufficient for the 18" AI states. They determined that a Prime every 12" would be capable of keeping SPS with LPS and other lower light corals lower in the tank. They did a video on it some time ago, i'm sure you could find it on their website.