par 38 bulbs on nano

[jaynel78]

Hello does anyone have experience with the par 38 bulbs how many would you need on a 12gal tank...thanks

[WingoLED]

Depends on the dimension, height of the bulb from the water and power of the bulb, here are some par data for your reference in different scenarios:
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[jaynel78]

thanks for the chart...whats average for height off the water 6"-8" maybe...

[Donniegnzls]

36 inches form bottom of the sand to bottom of the bulb for LPS. For SPS/clams I would do 25 - 30 inches from bottom of the sand. lower as needed. SPS LPS turn brown. Lower the light or add a second.

[KafudaFish]

Originally Posted by Donniegnzls

36 inches form bottom of the sand to bottom of the bulb for LPS. For SPS/clams I would do 25 - 30 inches from bottom of the sand. lower as needed. SPS LPS turn brown. Lower the light or add a second.

Never understood why someone would have a 12 inch tall tank but hang their bulb 2 feet off the water's surface.

[Donniegnzls]

Because its only 12 inch tall is exactly why. The less water the light has to penatrate the higher the par will be. Water acts as a sun screen so to speak. This is why you see lights so high on the short frag tanks. Another reason is because PAR 38 bulbs are like lazor beems with those reflectors and the farther you can have them away the better the par spread will be but too far and you wont have enough par. These Par 38 bulbs are designed to spot light in deeper tanks. Not deep tanks but deeper than 12". So to close and shallow water = cooked coral. But would most likly only cook what is inside a 6 inch circle at that distance.

The below picture shows a PAR 38 over a 30 Gallon at 35" from the sand bed. The tank is 18" tall.

The other picture shows my 58 Gallon tank that is 21 1/2" tall and the lights are 26 inches from the sandbed.

I used to run that PAR 38 over my 28JBJ about 35" away with a hammer coral toward the outside, clam on the bottom and riccordia in the middle and center of the tank. The riccordia got a little burned but adjusted. I then added a SPS Acro to the top center and lowered the light to high 20's and the riccordia burned up and I had to move it out to the edge. I dont recommend these lights on nano tanks. As I said before they are for spotlighting in bigger tanks not as a nano tank light but they can work. In fact almost all lights are made for 18-26" tall tanks and this is why we must have them farther away from the shallower tanks.

[Donniegnzls]

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[jaynel78]

thanks for the info

[KafudaFish]

Originally Posted by Donniegnzls

Because its only 12 inch tall is exactly why. The less water the light has to penatrate the higher the par will be. Water acts as a sun screen so to speak. This is why you see lights so high on the short frag tanks. Another reason is because PAR 38 bulbs are like lazor beems with those reflectors and the farther you can have them away the better the par spread will be but too far and you wont have enough par. These Par 38 bulbs are designed to spot light in deeper tanks. Not deep tanks but deeper than 12". So to close and shallow water = cooked coral. But would most likly only cook what is inside a 6 inch circle at that distance.

The below picture shows a PAR 38 over a 30 Gallon at 35" from the sand bed. The tank is 18" tall.

The other picture shows my 58 Gallon tank that is 21 1/2" tall and the lights are 26 inches from the sandbed.

I used to run that PAR 38 over my 28JBJ about 35" away with a hammer coral toward the outside, clam on the bottom and riccordia in the middle and center of the tank. The riccordia got a little burned but adjusted. I then added a SPS Acro to the top center and lowered the light to high 20's and the riccordia burned up and I had to move it out to the edge. I dont recommend these lights on nano tanks. As I said before they are for spotlighting in bigger tanks not as a nano tank light but they can work. In fact almost all lights are made for 18-26" tall tanks and this is why we must have them farther away from the shallower tanks.

I was not referring to the mechanics of how different wavelengths of visible light were filtered out of the water as you increased water depth. I understand that and most other reefers do also. I meant that the ascetics of having a blinding light so far above the tank is unpleasing to my eyes. It is like playing basketball in my drive way at night and the flood light is right behind the clear backboard. Sure I can see things but what is the point?

As far as people burning their corals many did not properly acclimate them to a change in intensity. I don’t know how you did your tank and I am not saying that you did but when the LED craze hit people where commenting on how the lights were not powerful and that was followed by how they were bleaching their corals. You still see that today even with all of the discussions.

If you look through the nano section on RC and on other sites you will see people running these bulbs on their nano and pico tanks without issue. For you to say that one should not do it because you will kill everything in the tank does not make much sense as long as the corals are properly acclimated to the light intensities.

I would have no problem running a pair of PAR 38 LEDs on a 12 gallon tank if my aquascaping and coral selection required it such as two bommies vs. the use of a single PAR 38 on a single island.