The Planted Tank Forum - View Single Post - 45G, Too much light for a high light tank?
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post #2 of (permalink) Old 01-24-2013, 08:55 PM
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Join Date: Apr 2007
Location: Delaware
Posts: 1,600
Originally Posted by parker679 View Post
45G Tank (36 X 13 X 24)
2 - 36inch Odyssea 2 bulb T5HO sets. 78W per set. My understanding is that these use an inferior ballast/reflector and thus behave more like T5NO with regards to light output.
Aprox. 2 inches of substrate and light sits one inch above tank
Pressurized CO2, lime green 5dkh drop checker
Dose PPS Pro, currently just the macros per PPS and micros via Flourish until I finish the bottle

When I started I had one light set and no CO2. Before I knew about the whole par thing I got a second set to get closer to 3-4wpg. I got algae and started to research more. I found Hoppy's chart and according to it I was at 40 par with one set which he considered square in the middle of the medium lighting spectrum. So I figured 2 sets would be high light and I got a CO2 set up and started dosing PPS Pro.

I know having 2 lights doesn't double the par exactly, only on those areas where the light spread overlaps.

My question is, is this too much light and where is the max threshold for high light before having more is counter productive?

I would prefer not drop to one set because it would put me back in the medium light range. I'm thinking maybe if I raise them 6 inches above the tank that will put the light 28 inches from the substrate and put me in the area of 60 par where the light spread overlaps.

Thoughts? Or is my understanding of all this just completely wrong? Thanks!
I have 4 x 39watt T5HO under Ice Cap reflectors over a 30gal tank (17in high). Distance from the base of the lamp to substrate is 26in, so no you do not have high light. Don't overly worry about what Par you're lamp outputting, just watch the plants growth. No color = lights...nutrients, leggy growth= lights, poor leaf and or overall poor plant growth back off lighting and focus on nutrients and Co2..etc. You get the idea.

Don't get caught up in Par

The Junkie

Last edited by mrkookm; 01-25-2013 at 04:11 AM. Reason: .....
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