Decision with 250W or 400W Iwasaki

[Ermin]

I'm running two 250W Iwasaki with two VHOs right now over my 100g tank.

I like to upgrade to either:
1.) Two more 250W Iwasakis
or
2.) Replace the existing lights with two 400W Iwasakis.

Which one is a better deal? Price of the MH bulbs are the same. The a dual 400W ballast is only around $6 more. I read on Sanjay's MH bulb comparison that new 400W Iwasakis has around 203.7 PPFD, while the 250W has 104.5 PPFD.

If I take it watt for watt conparison....250W at two of them in my first option will yield 209 PPFD using 500W. 400W at one will yield 203.7 PPFD. Even though it is slightly less PAR, I'm saving 100W of energy. Is my assumption correct? Would this make the 400W upgrade a better deal?

[golfish]

Ermin,
I guess its time to come on over again[img]/ubb/smile.gif[/img] I'm running a 400 watt Iwasaki between the HQI's on a PFO standard ballast. Its a BUTT UGLY yellow\green but lots of light. I read the MV ballast gives the 400watt bulb a better color but still not as good as the 250's...I

[David Grigor]

IMO: Your assumption on par is incorrect.

You can't just add up the par of the 250s and compare to a 400W. The 250s you would just spread the 107 par over a larger area with possibly a little higher in some of the overlap. With the 400W you would get 176+ par over the same area as one 250.



[This message has been edited by David Grigor (edited 05-09-2001).]