How long to leave lights on 75g?

[kjacks]

I have a 75g plant tank with pressurized co2 and (6) 54watt t5s.. (6700k). How long should they be on?

[CatSoup]

I have heard 12 hours, but I think a min of leaving them off overnight is good.

[D.gilly]

I'd start at 8 or 9 and work up to 12 over a few weeks sometimes pushing the lights too long at the beginning when the plants are just starting to grow can cause algae.

[BBradbury]

Originally Posted by kjacks

I have a 75g plant tank with pressurized co2 and (6) 54watt t5s.. (6700k). How long should they be on?

Hello k...

Most of our aquarium plants come from tropical places, so they're used to long hours of daylight. I have my tank lights on timers set for 12 hours on and 12 off. If you want good plant growth, 10 hours is probably the minimum and 14 the maximum.

B

[Kathyy]

A 4' long tank with 6 T5 bulbs? If the bulbs are 54 watts then then they are high intensity and you have about 3x the amount of light you need. I would turn off 4 of them and run for 6-8 hours a day. If you cannot do that then raise the fixture a foot or so and put common fiberglass window screen on top of the tank as a shade cloth. Are you running CO2? If not then reduce the lighting intensity even more.

A tank with 6 bulbs over it will likely need added nitrate, phosphate as well as the usual potassium and micros plus CO2 at a high rate with very good circulation so oxygen is at a very good level as well. Most people on this forum have lighting periods of 6-8 hours with such a set up.

If the plants do fine and you don't run into any algae then do increase the lighting period, lower the lights, increase the number of bulbs running and remove the window screen a little at a time.

[kjacks]

Originally Posted by Kathyy

A 4' long tank with 6 T5 bulbs? If the bulbs are 54 watts then then they are high intensity and you have about 3x the amount of light you need. I would turn off 4 of them and run for 6-8 hours a day. If you cannot do that then raise the fixture a foot or so and put common fiberglass window screen on top of the tank as a shade cloth. Are you running CO2? If not then reduce the lighting intensity even more.

A tank with 6 bulbs over it will likely need added nitrate, phosphate as well as the usual potassium and micros plus CO2 at a high rate with very good circulation so oxygen is at a very good level as well. Most people on this forum have lighting periods of 6-8 hours with such a set up.

If the plants do fine and you don't run into any algae then do increase the lighting period, lower the lights, increase the number of bulbs running and remove the window screen a little at a time.

I am running pressurized co2 via a ph controller set at 6.8.. I am using the full line of seachem frets with they're dosing schedule. 3" of flourite. I currently have the lights on separate timers so it give the effect of a dawn and dusk period. Should i just get rid of two bulbs all together? Just want to do the rite thing and not just kill a bunch of fish and plants..

[mistergreen]

I would use 2 or 3 bulbs. Too much light isn't the best even with co2.

[CatSoup]

Wattage amount is something I've wondered about for my own tank. I have 2 54 watt lights on my 55. From this thread's responses I am guessing that's pretty perfect. Correct?