View Full Version : How many hours of light for my plants?

04-06-2010, 12:52 AM
I upgraded my light fixture to 40W (29g tank) and picked up a bundle of java moss and a scraggly looking java fern. How many hours a day should I leave the light on now that I'm supporting plants?

04-06-2010, 12:53 AM
10 hours should be plenty. A timer is a good investment.

04-06-2010, 01:13 AM
You should be fine with 10, but if you start having problems with algae, cut it back to 8. Java Moss and Java Ferns are slow growers, so if you over feed, they won't abosrb excess nutrients at high rates.

Lady Hobbs
04-06-2010, 01:29 AM
10 for me, too.

04-06-2010, 01:31 AM
9-10 is fine. Oh and java moss is not nearly a slow grower. It grows as fast as weeds.

04-06-2010, 01:33 AM
I've heard disagreement on both of these plants being "slow growers" or "fast growers". As someone who's never grown aquarium plants before, I guess my question is, "compared to what?"

Also, I have a timer, so that's good. Can I break the 10 hours up into two separate chunks (nobody is around to enjoy the view in the middle of the day), or would that screw with things?

04-06-2010, 01:43 AM
I've heard that breaking up the time your lights is on can be bad for your plants

I have mine on form noon until 8:00pm.

04-06-2010, 01:48 AM
I run from 2 to 12 that way they are on the whole time I am home and awake with time to watch the tanks.

You can split the photo period if you wish.

04-06-2010, 06:09 AM
Really it'll depend on many factors, the types of plants, how much algae you get, if you are adding other carbon sources for the plants. Personally I run most of my tanks around 7 hours at the moment. Since it's getting much warmer outside, I've switched the lighting hours from the day to the evening. I have the lighting turn on around 5 and turn off around midnight. Helps cut down on the heat in the aquariums.

It'll take a while to dial in the right amount of hours you'll need to run lights. If it looks like the plants need more light, leave them on longer. If you end up getting too much algae cut back the hours.

Z Fish Man
04-06-2010, 06:58 AM
Ive read on these forums that breaking up the light time is better to control algae as they can deal with the break in photo period like plants can. I can't provide any scientific evidence for this though.

04-06-2010, 01:12 PM
9-10 is fine. Oh and java moss is not nearly a slow grower. It grows as fast as weeds.

I'm not going to argue with you.

The stuff grows like weeds in some tanks, not all of them. I have some and it's growing slowly while it grows like weeds in my LFS's tanks because they have tons of light over it.

The stuff I have came from my LFS.

Wild Turkey
04-06-2010, 01:58 PM
12/12 here. No algae problems

went up to 14 once and got plenty of algae, though.

Plant Man
04-07-2010, 12:25 AM
Java Moss and Fern grow very fast if the Co2 and light are there. 20-30ppm Co2 and 1.8+ watts per gallon change 10-15% water once a week and you'll have them growing like weeds. Hell, they are weeds!

Plant Man
04-07-2010, 12:30 AM
Sorry, I meant to post pic,