[Wet Thumb Forum]-Lighting Q - DIY Aquarium Projects

dissident · 08-20-2004, 07:28 PM

For all you pros out there what would you go with for a 240gal tank. 72Lx24Dx31H
Priceing everyhting out MH and PC ends up being about a $30 difference to get 5w/gal. Due to the depth of the water I am leaning more towards the MH solution.

MH
3x400W
(1) 10k
(2) 6500k

PC
16x65W
(4) 10k
(12) 6500k

Thanks in advance.

They won't all be running at the same time as in a dusk-dawn type mode. I really want to start keeping some high light demanding plants, will be using an in-line CO2 reactor.

dissident · 08-20-2004, 07:28 PM

For all you pros out there what would you go with for a 240gal tank. 72Lx24Dx31H
Priceing everyhting out MH and PC ends up being about a $30 difference to get 5w/gal. Due to the depth of the water I am leaning more towards the MH solution.

MH
3x400W
(1) 10k
(2) 6500k

PC
16x65W
(4) 10k
(12) 6500k

Thanks in advance.

They won't all be running at the same time as in a dusk-dawn type mode. I really want to start keeping some high light demanding plants, will be using an in-line CO2 reactor.

nino · 08-20-2004, 07:38 PM

Definitely MH for a tank that deep.

hubbahubbahehe · 08-20-2004, 07:42 PM

i would pick 3 x 400 just cuz it's so much easier to handle....you gotta take care of 16 bulbs?!?! vs 3??!?! the KISS method is very applicable here. Good luck..

btw, you don't need that much lighting for a 240....you could do fine with 4 x 200 w

bharada · 08-20-2004, 08:41 PM

If your tank is braced every 24" then definitely go with the MH (although 3x400w may be overkill, 3x250 would probably do). I just picked up a 125 (72x18x20) and was contemplating the same thing as you as far as lighting it goes. As I bought it through an online ad for an estate sale, I didn't actually see the tank until I picked it up this afternoon.

Long story short, I was anticipating a standard AGA tank with 24" spacing between the braces...wrong, only a single center brace with some additional glass bracing on either side of it. So the MH pendants wouldn't have worked as the center pendant would have been over the brace casting a nice big shadow down the center of the tank. I opted for 4 96w PC fixtures instead.

Rex Grigg · 08-21-2004, 02:49 AM

5 watts per gallon on a 250 gallon tank is WAY too much light. Unless it's going to be a reef tank. At most on a tank that size you might need 2.5-3.0 wpg. One thing to remember is the MH bulbs are expensive and have a short life span. Consider that you are going to have to replace bulbs every 18 months or so with the MH lights. Consider that you can pretty much run the PC bulbs till they die. Consider the fact that you are shooting for way too much light. Now figure out the actual starting costs and then the Total Cost of Ownership.

I can tell you that I would start with 384 watts (4x96 PC) and then if I needed more I would add another 192 watts (2x96) watts.

The watt per gallon rule really breaks down on tanks this size. And it breaks really low.

If you have your heart set on MH lights then I would recommend 3x175, or maybe 2x175 and 1x250 at the most. Run the 175s on the sides and the 250 in the middle.

Laith · 08-21-2004, 04:20 AM

Rex: "Consider that you can pretty much run the PC bulbs till they die."

Really? I had always thought that *all* flourescents loose much of their efficiency (for plant growth at least) after 6 to 9 months.

I don't have PCs but use T8s and I change them out every 6 months. Am I overdoing it?

Would love to hear that I am!

Gets expensive changing so often!

Hawkeye · 08-21-2004, 10:42 AM

NO fluorescent do only last about 6 months. But PC can last till they die. They loose some brightness after a few months and I have read that PC should be replaced every year or so but I have bulbs well over 2 years old now without any problems. I have read where some people have used PC bulbs longer without any trouble. I have changed all my tanks over to PC. The only time I change bulbs is to try different K bulbs or they die. Its cost more up front but replacing NO bulbs over 6 tanks was a real cost/year.

Hawk

dissident · 08-21-2004, 05:35 PM

Thanks for all the input guys. I might consider a 180gal which is 6inches shorter then the 240. Since the cost difference would be much more with the suggestions I have gotten. I will then probably go the PC route. Since the advised MH lighting solution will definatly cost more then the PC by a few bills. But, I also change my mind a lot, and I have 4 weeks before I order out the tank.

From your experiences would the PC route work for the 240gal fro growing a nice glosso carpet?

Thanks again

Rex Grigg · 08-22-2004, 05:09 PM

With good reflectors you should not have a problem. However 31" is a deep tank. The one advantage that MH lights have is that they are a point light source. PC lights are a more diffuse source of light. But all in all I think that you would be able to grow a Glosso carpet in a 240 gallon tank. But I do want pictures of you trying to plant it in a tank that deep.