Further lighting question

[Inkwell]

The sticky on lighting helped me a lot. I have been out of reef keeping for some 15 years and lots has changed. My question is whether there is a rule of thumb on the penetration depths of LEDs if I desire to keep mixed corals. I am looking at a tank around 125 gallons. The AGA glass 125 is listed at 72x18x21. The glasscages acrylic 125 wide is listed as 72x24x17. Is the difference between 17 and 21 inches enough extra depth to dictate moving from LED to MH for the extra penetration? I remember the heat, cost and crazy electric bills from adding MH in the past, It ended up prompting a chiller purchase further eroding my budget. Obviously I can mitigate the extra depth issues by proper placement of specimens higher or lower to accommodate their light needs . . . if they are inclined to stay put.
Thanks!

 

[RockStacker]

The extra 4 inches of water depth generally is a non-issue, specially when comparing 17" and 21".

 

[Inkwell]

so even for the taller 21", the proper LED lighting will give plenty of penetration and good PAR measured at the sand bed. Let me now turn the question around. Is it worth buying the same tank but with a 24" height (presumably a 180)? Obviously larger mass of water means more stable environment plus more height means room for vertical coral growth, but now I am comparing a 7" difference from 17 to 24. I know most of this hobby is about balance so where do I get diminishing returns on tank height because of light penetration petering out? I recognize I am probably overthinking a very simple part of the process but before you start is the best time for that I suppose. I know it is common to skip a 55 and go to a 70 because 6" more front to back is huge. Just not sure about increasing height.

 

[salt_for_brains]

Welcome to the site!!

Personally, I didn't like that height b/c it was tough for me to reach some areas.

I had a 150g that was 24" deep that I ran 4 vho and 2- 400w MH's on with excellent growth no matter where the corals were located. I since sold the tank and the guy that bought it from me installed Ecotech LEDs. The same corals are still thriving in basically the same areas I had them. You are going to get good PAR from either now of course there are also better and/or cheaper versions from both. I wouldn't be scared in the least if I wanted to run LEDs on a 24" deep tank and that goes for MH's as well. You won't have every coral in the sand bed and will be placing some in the rock so you gain inches there on your more light demanding corals.

Also remember if you have a sand bed that is 2" you now have 22" instead of 24".

 

[Inkwell]

makes sense. so the two things I take away are:
1. presuming quality components, the difference, if any, between MH and LED in terms of penetration are close enough to be a non factor
2. while there is a sizable difference between 24" and 17" in height, it can be mitigated by proper placement on the rock structure.

And we didn't even touch on optics where the balancing act starts all over between penetration and spread but I guess you just get the manufacturers input on that and go with it

 

[fastrd400]

I am running Ecotech Radions on a 24" high tank. I have sps at the bottom that is doing fine. I suggest you do in depth research on whatever LED lighting you are thinking about. There are quite a few threads on forums about each light, it's penetration, and any trobles if any people may be experiencing.