I have a 150w MH
w/2 65w blues over a 29G and it can take the temp 2 degrees up over 5 hours. It very much depends on what the temp is in the room. This tank is upstairs and the temp (room t emp) can be controlled much better up there than in my downstairs. I imagine during the summer its going to be very hard to keep the temp in the mh
tank stable as it will get very hot where I live in the summer (Can get into the 100's easy). My point being, that if you live in an area where you can expect very hot temps outside, you can expect its going to get pretty warm inside. If the temp in your house is 78, the tanks going to be *at least* that much which means another 5 - 8 hours of mh
lights (even dual 175's) are going to cost you another couple degrees (Min). So at the end of a 5 hour cycle your tank temp would be about 80.? degrees. Now, barring the fact you may have a pile of money or an industrial AC
unit on your house, you'll probably end up with a chiller, running your AC
all the time every day through out summer or dealing with high tank temps (usually treated by moving the cycle to cooler evening hours and using a fan (like a room fan) to blow across the lights to try and exhaust some of the excess heat..Great for the fish, not so much fun for the rest of the family..). All that said, even using 4 VHO
's I get a degree or two of flux and during the summer my tank can easily start to reach 82.? degrees. Its a given that mh
produces more heat and that can only mean higher temps. You can put what ever wattage bulb you want over the tank, the fact is mh
*is* hotter and will cause substantially more temp issues during warmer weather. Again, I have seen chillers used, I have seen folks run their thermostat (in the house) around 74 - 72, but imo
, thats not practical. I can't afford a $250/month cooling bill ; ) So in the end, you either realize mh
may cost you a $400 - $800 chiller (plus the cost of running that each month) or run cooler lighting/change the light cycle to cooler hours..Not much fun to look at the fishies in the dark when you get home from work..
Just punchin' in with my experience, some of you surely live in cooler climates and may not have this issue.