Downgrading Lighting?

[bumwrok]

I have a 20 long that has a 175mh 10k with 28w t5 actinic for blue. The problem is the metal halide ballast is a P.O.S and I'm really concerned about it burning down my house while I'm at work. I have some VHO ballasts left over from another tank that can easily support 2ft 75w 50/50 bulbs and my hood has room for 4 bulbs total.

I have only softies and LPS. My question is, should I use four 73w VHO's and have 14.6 watts per gallon or 2 bulbs and have 7.3 watts per gallon? I know 7.3wpg is fine for the corals I have, I just need to know if I should use more watts if I'm using VHO's than I would with Metal halides.

[NapoliNewJersey]

14.6 watts is over kill ... 7.3 is more than enough for LPS and softies.

[bumwrok]

Thanks man.

So I take it that the type of light source (MH, VHO, or PC) doesn't matter only the amount of wattage.

[dorkfish]

Thanks man.

So I take it that the type of light source (MH, VHO, or PC) doesn't matter only the amount of wattage.

No, that is completely wrong... Wattage is nothing more than a measure of how much power a fixture is using. What you need to be concerned about is PAR- photosyntheticaly available radiation.

I would agree that 4 tubes is overkill... no reason you can't do it though, except you might have to acclimate the corals to the light level. I don't know the numbers off hand, but metal halides in general out out a lot more par per watt than VHO... so you would deinitely be going down in light level (wattage alone indicates this) with 2 tubes... with 4 you might end up a little higher.

[drobes]

A 20 gallon long is only 13 inches tall. You really don't need that much light for LPS and softies and in fact it may limit places that you could place moderate - low light corals.

2 VHO bulbs with a T5 actinic supplement would be less light than what you have now but should work fine for LPS and softies. Also you could run 3 VHO bulbs on that ballast, it just means you're doing the wiring diagram differently. Are you sure your actinic supplement is T5? I'm not familiar with a 28W T5 bulb.

[bumwrok]

A 20 gallon long is only 13 inches tall. You really don't need that much light for LPS and softies and in fact it may limit places that you could place moderate - low light corals.

2 VHO bulbs with a T5 actinic supplement would be less light than what you have now but should work fine for LPS and softies. Also you could run 3 VHO bulbs on that ballast, it just means you're doing the wiring diagram differently. Are you sure your actinic supplement is T5? I'm not familiar with a 28W T5 bulb.

Thanks that answers my question perfectly. It's a fixture with two 14w actinic t5 bulbs.

[drobes]

Thanks that answers my question perfectly. It's a fixture with two 14w actinic t5 bulbs.

Ah, that makes sense. Good luck with your tank!