looking for a straight answer regarding my lighting

[beedee]

tank- 11.4g mr aqua, "18.9" x 11.8" x 11.8"
light- AquaticLife 20" T5HO, currently 2x 18w, 10k bulbs
substrate- Yubao
flora- HC, Hemianthus callitrichoides
hardscape- 7 Seiryu stones
co2- yes, once i fill it. 24oz paintball set up

My tank is currently in a dry start method, and I just added the AquaticLife lighting this past Sunday, prior to that, I had two Jebo 13w, 6500k clip-on lights, 12hr photoperiod. The AquaticLife fixture is sitting about 2.5" above the tank (via the legs it came with), and about 12" above the substrate.

I understand that my new lighting is bright, and it can probably be seen from space, so I am looking to dial it in. This is where I need your help. Hanging my fixture isn't really an option, so...

Should I use?

• 1 18w, 10k?
• 1 18w, 6k?

Also, is using the 2x 18w, 10k during my dry start overkill?

[Hoppy]

About the only fix available to you is using window screen, fiberglass insect screen from Home Depot, between the light and the tank. Each layer reduces the light intensity by about 40%, so one layer leaves you with 60%, two layers leaves you with 36%, 3 layers leaves you with 22%, etc. If that light has even moderately good reflectors you will need 3 layers of screen to drop the intensity to a good level.

[HolyAngel]

agreed, a 12" tall tank would be fine with just a single t8 on it and no co2. 2 with co2. otherwise just 1 t5ho and yeah, will definitely need screening or have to raise it a good 12"+ off the top of the tank to have manageable lighting.

[TactusMortus]

Can't really help you with the lighting distance as others have said everything there is to be said with that. However I can say during the dry start method you shouldn't have a problem. As from my experience you can run far more light during the dry start. The reason being the co2 is readily available to the plants. Compared to being submerged when it becomes far more difficult to maintain adequate co2.

[wetworks]

Originally Posted by Hoppy

About the only fix available to you is using window screen, fiberglass insect screen from Home Depot, between the light and the tank. Each layer reduces the light intensity by about 40%, so one layer leaves you with 60%, two layers leaves you with 36%, 3 layers leaves you with 22%, etc. If that light has even moderately good reflectors you will need 3 layers of screen to drop the intensity to a good level.

This is a great tip!

[jasa73]

Yes with respect to dry start, i dont think you have anything to worry about with using 2x18w.

Also remember that when you fill your tank, not as much light will reach the bottom and you may think its not so bright. You'll need good light (along with your ferts and c02) to keep that HC carpet nice. I would say, let your plants tell you if its too bright or not.

[TactusMortus]

I think you are underestimating just how shallow the tank he has is jasa73 it is less then 12 inches deep when you add substrate you are looking at more like 10 inches. There is no way he is not going to have to much lighting once filled.

[beedee]

thanks everyone! i like the idea of getting some screen and putting it between the light and the tank, seems like a very easy fix. especially because the bottom of the fixture has an acrylic cover that the screen can just lay on top of.

the substrate does slope from low in the front to higher in the back by about 2". so the light is 12" above the substrate in the front, and about 10" above it in the back.