How much more heat if you go from 175W to 250W

2 IceCap fans that run 24/7.

I've been running with this temp swing for 2+ years w/o a problem, but
turning the fans off is something to consider. Don't shallow reefs have a
swing of 10-15 degree's?

Thanks!
LT

"Dragon Slayer" wrote in message
...
i'd be worried most about the 6 deg temp swing you have now, IMO thats to
much of a swing in a 24 hr period. are you running the fan's when lights
are off? doing this will give a greater swing in temp, not doing it gives
a
higher tank avg temp.


kc

"ljtellef" wrote in message
...
Hello!

I am thinking about going from 175W MH's to 250W MH's so I can run the
Iwasaki 6500k's.

My concern is the increase in heat. I understand that there is some
formula
that converts a watt to a BTU, but is it safe to assume there is a
linear
relationship for heat? IOW...the 250W has 43% more watts than a 175W.
Should I assume that they will put out 43% more heat? If my temperature
increases by 6 degree's during my photoperiod, should I plan for 8.58
degree's (6 x 1.43)?

Does anyone have suggestions on ballasts? I read Sanjay's paper on
ballasts
and it appears that any magnetic (tar, core & coil, etc) ballast is the
best
for PPFD and output for the 250W Iwasaki. Anyone know of any updates or
new
info since this was published?

Also, if you are interested in purchasing or trading, I have (6 month
old)
a
175W double CSL ballast and a single.

Thanks!
LarryT