5g custom build cycling. Have lighting question - Pic


Premium Member
The tank is still presently cycling. The lighting is the Viper 150w HQI.

Presently, the light is 11 inches off of the water surface. What I'm not sure of, is ideally, how far off the water surface should it be?

Any thoughts are greatly appreciated! Thank you!



New member
you mean you have 150 W over a 5 G tank? wow

I would imagine, you can put the light as close or far as want, depending on what you want to keep in there.

I would think, when you come home from work, that maybe 2-3 G out of 5 would be evaporated?


Premium Member
LOL! I know, and you would think it would be enough to heat the water, which is what I was accounting for, but amazingly, it is not heating up the water much more above room temp.

As for evaporation, I have noticed that and expected it somewhat. For the last week, I've topped off in AM before work and PM after work. So far, my evaporation rate has been a little less than a cup, which is affecting my SG by about .001 - .002 per day. I have the SG set at 1.023. It's been reading 1.024 - 1.025 when I get home b/c of evap.

I'm curious to see what effect, if any it has on what I put in there.

I had the tank made at an LFS. They've had 3 on display in the store for about a year now. I've been going there for about 4 months or so, so I was taking their word on how long they've had theirs.

They said that they have the same evap issue, but the slight SG change has not been an issue with anything they've put in yet, albeit, all they have are some shrooms, polyps & zoa's. One crab, one shrimp and one tank raised clown that's smaller than a dime! LOL!


New member
Small salinity changes are normal in the ocean. You can go as low as you want on the light as long as there is no splashing hitting and it doesn't affect your temp to much


Premium Member
Thanks silverwolf. Well, the temp isn't an issue as I can't even raise the water temp as it is now.

It looks like I'm actually going to need to add a heater. I can't get temp above 75 with lights alone, and that's with a 12 hour photo period.


The Reef Producer
using your lighting as your primary heat source would be a bad way to go.

temperature fluctuations are not good...

even if your mh was enough to heat the water, i would still have a heater to hold that same temp during the night.