how do i know how much light i need?

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

toyotasrfun

Aquarium Advice Apprentice
Joined
Mar 21, 2006
Messages
16
hey
so here's the thing
i should be putting the deposit on my 225 gallon aquarium this coming week
now what i'm wondering is this..
i'de like to build a light setup for the aquarium..
i went to the local hardware store.. they have metal halide stuff i can buy, they have t5 stuff i can buy and they have t12 stuff i can buy
what bulbs are going to be enough to grow high light plants like madagascar lace, etc?
here are the dimensions of my tank
72"x24"x30"
the tank will indeed be 30 inches in height..
i realize i will need lots of light.. help is appreciated..
 
I'm not sure about the wattage, but I think alot of people that have big tanks go with metal halides that they hang over the tank. If not the MHs, then I'd build some type of setup that holds alot of compact fluorescent bulbs and hangs over the tank from the ceiling.

I think a madagascar lace plant is either medium or high light, so I'd go with 2-3wpg. 2wpg would be 450 watts of light. I'm not sure if the wpg rule applies to the MHs though.

Hope I helped a little....I'm sure some of the experts can tell you more.
 
One thing with metal halides, I don't think they focus on any particular spectrums for plants, but is just strong light over-all. Some say they work, and others say they don't for planted tanks. I have no experience with them.

But if you want a good light system for the tank, look for t-5's. Or if you make your own hood, install t-5's in the hood. Will probably be quite a bit cheaper, and the bulbs are excellent for plants. Just look for around 400W-500W in lighting for that tank. Or you can go a little higher for more plants as well, but remember one thing, even with the 400W, you will definitely need to inject CO2.
 
see.. that's where it gets confusing.. i'm told that it's all dependant on lumens and junk..
variables like the depth of thetank.. all that fun stuff..
some say a general rule to follow is 2 wpg for growing high light plants..
i figure i'll need to start with co2 injection for this new tank... AHHHHHH.. that's gonna be a fun like pulling teeth without novacaine.. ah well..
things i do to enjoy the hobby.. hehe
anyhow.. i'm going to check home depot specifically for lights tomorrow
i'll let you guys know how that goes
thanks for the help so far!
to tomorrow!
 
2wpg is medium light plants and you don't need CO2 with that light. When you get around 3wpg and above, then you need CO2 to avoid algae problems.
 
Here's a guesstimate of the lighting levels that various amounts of light would provide you. Don't forget to add an extra 25% due to the height of you tank.

The size of your tank means that you won't need as much light to reach each of the lighting levels. Even at 2WPG in smaller tanks, it's sometimes necessary to add CO2 to keep algae at bay. Medium to Medium High Light is that grey area where you may or may not actually need CO2. By the time you get to High Light CO2 becomes a definate must. I'd recommend planning on having CO2 if you go with medium or better lighting. This way you're already covered if you need it and it's beneficial to your plants even if you don't need it.

Something to keep in mind with light fixtures from hardware stores, is that they are designed to light a room not a small area like a tank. While a lot less expensive the light from those fixtures is going to be less useful since a large portion will get reflected out instead of down. You can compensate by adding some extra light or by replacing or modding the reflector so that light is directed mostly into the tank.

Don't forget about ferts as you're doing your planning. Even at Low Light Levels you would need at least Micros and Potassium, if you go with Medium or better you are looking at needing Nitrates and Phosphates as well.
 
Metal Halides are the best type of lighting for plants. They have a very smooth spectral output without the spikes that Fluorescent have. for a high-very high light plant like lace swords, you would need ~3 250 MH lights running 6500K - 10000K bulbs. Using CF fixtures you would need a lot of fixtures, not only that but mounting them could get a bit tedious. (~ 6-8 x 96W bulbs). T8 are slightly more efficient, esp. if you research ODNO. You could use 4 Dual T8 fixtures (hanging shoplights) at ODNO 4x (~ cost is 80-140USD with 8x Philips daylight deluxe).. This would be the most cost effective (and easily obtainable)..

You would need to get 4 x Shoplights (I think they are about 10$ down there), 8 x (4x32w ballasts) which can be purchased at home depot or on Ebay.. Alternately you can use 6 x shoplights at 2 x ODNO (6 fixtures, 6 2x32w ballasts) which might be cheaper.. depends on the price you get for the ballasts.
 
Back
Top Bottom