MH above the water line

[wagnerke]

What is the closest you can place a MH setup to the water and
how much will the water temp rise? I have purchased a dual 175
watt setup with Ushio 10,000K bulbs.

-Kevin

 

[Ben1]

4" would be min I would recommend with 175's. It will raise the water temp a few degrees unless you have decent fans in the hood. You can hook the fans up to a controller if you want so the run as the tank temp goes up or just run them on the same timer as the lights.

I use a 175 6" above my 40 tall, and used to use dual 400's 6-7" above my 75.

HTH

 

[wagnerke]

Thanks for the reply Ben.

At this point if I install it into my oak hood it would be about 7 inches above the water. My other thought was when it heats the water, will it keep it between 80 to 85 degrees. This way I wouldn't need a heater. Any thoughts?

 

[Anonymous]

You will need a heater because when the lights are off, the temp will plummet. The main problem is really temperture fluctuation.

Also, IMO 85 is too hot.

:mrgreen:

 

[wagnerke]

Good point Righty. Guess I wasn't thinking how fast water cools. Thanks for the reply.

-Kevin

 

[wagnerke]

One more question. How long should you keep MH's lite. Is 6 or maybe 8 hours?

-Kevin

 

[TomH]

In response to your first question. . . . I've got a 175 and a 250 about 5-6" above the water on my 72. I've found that with the apt's air conditioner set at 74 or so, all I really need to keep the water temp at about 80 is a 12" house fan blowing across the sump. It's really amazing (and quite a relief) to watch the water temp plummet when I kick the fan on --you wouldn't think that evaporation can cause so much cooling, but it apparently does.

 

[clyde]

no fan cooling, tank water does NOT plummet that fast.

it takes a while.

heck look at lakes in the winter, its been like 30 degrees for like 3 weeks and its STILL not frozen over

but seriously, the glass of the tank, and stuff running in the tank, it goes down rather slowly but steadily.

 

[Ben1]

I would run 10 hours on the MH and have it turn on 1 hour after actinics in the AM and turn off 1 hour before the actinics in the pm.

This gives a strong 12 hour light cycle, about cooling yes a heater is still needed.

HTH

 

[TomH]

no fan cooling, tank water does NOT plummet that fast.

it takes a while.

heck look at lakes in the winter, its been like 30 degrees for like 3 weeks and its STILL not frozen over

but seriously, the glass of the tank, and stuff running in the tank, it goes down rather slowly but steadily.

When you're speaking of a temp change of 1-2 degrees, it does change that quickly. The fan blowing over the sump of my tank has drawn the temp down 1.5 degrees over the course of a half-hour. Though "plummet" may have been a bit of an overstatement, when the temp has started to creep up, it certainly feels like a "plummet" from 83.5 to 82.

 

[wagnerke]

Thanks everyone for your replies. I now have a good idea of what I need to do.

-Kevin