Wrapping my brain around Light Intensity
Planted Tank Forums
Your Tanks Image Hosting *Tank Tracker * Plant Profiles Fish Profiles Planted Tank Guide Photo Gallery Articles

Go Back   The Planted Tank Forum > Specific Aspects of a Planted Tank > Lighting


Reply
 
Thread Tools Display Modes
Old 03-23-2012, 09:54 PM   #1
SinisterSOB
Algae Grower
 
PTrader: (0/0%)
Join Date: Mar 2012
Location: C At Hell
Posts: 25
Default

Wrapping my brain around Light Intensity


Hello,

I am looking for some advice from lighting guru's about my T5HO set up.

125g (72" L x 18" W x 20" H)

I'm currently running 2 48" T5HO 54w bulbs, but have to fight off algae on a constant basis. These fixtures are about 9" above the tank, and from what I've read on this forum this would give me High Intensity Lighting.

I am looking to change my light set up. I would like to change my lighting to 2 24" T5HO 24w bulbs, but have them sitting across the length of my tank and just a few inches above the top.

Would this new set up fix my problems with algae?

I dont have Co2, and cant really afford it at this time.

Would the light intensity drop from High to Medium, if each single bulb fixtures were over one half of the tank? The charts available on this forum would suggest that a single bulb over the entire tank would do this, but two bulbs which create a single light over the tank?

Everything I've read on this Lighting Forum has gone against what I've known for many years when dealing with aquatic plants, so its a little confusing to see such beautiful tanks with such low watts.

Any help is greatly appreciated.
SinisterSOB is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 03-23-2012, 11:27 PM   #2
Hoppy
Planted Tank Guru
 
Hoppy's Avatar
 
PTrader: (74/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 18,354
Default

For fluorescent bulbs, watts are a measure of the length of the bulb, not the brightness. If you think in those terms it is much easier to figure out what lights you need.

Your tank is 18 inches front to back depth, so one bulb sitting on top of the tank cannot light the whole substrate uniformly, and the plants will all grow towards the light. But, for the PAR that works best, you only need one bulb or row of bulbs along the length of the tank. If you separate the rows of bulbs by 6-8 inches or so, the PAR from two rows isn't significantly higher than from one row, but the light spreads out enough to cover the whole front to back depth much better. Here is one light fixture designed around that idea: http://www.catalinaaquarium.com/stor...oducts_id=1841 A pair of those, in a row, should light the tank very well.
__________________
Hoppy
Hoppy is online now   Reply With Quote Quick reply to this message
Old 03-23-2012, 11:48 PM   #3
SinisterSOB
Algae Grower
 
PTrader: (0/0%)
Join Date: Mar 2012
Location: C At Hell
Posts: 25
Default

Quote:
Originally Posted by Hoppy View Post
For fluorescent bulbs, watts are a measure of the length of the bulb, not the brightness. If you think in those terms it is much easier to figure out what lights you need.

Your tank is 18 inches front to back depth, so one bulb sitting on top of the tank cannot light the whole substrate uniformly, and the plants will all grow towards the light. But, for the PAR that works best, you only need one bulb or row of bulbs along the length of the tank. If you separate the rows of bulbs by 6-8 inches or so, the PAR from two rows isn't significantly higher than from one row, but the light spreads out enough to cover the whole front to back depth much better. Here is one light fixture designed around that idea: http://www.catalinaaquarium.com/stor...oducts_id=1841 A pair of those, in a row, should light the tank very well.

Thanks for the info Hoppy!

Those fixtures are great, but I wouldnt be able to justify spending $300 on lights to my wife.

If I were to get 4 24" fixtures and space them out over each side of my tank, would it be enough to cover the substrate? I have a Hydroponics shop that I visit often, and can get the 4 T5HO fixtures for half the price of the Catalina fixtures.

There is very thick piece of glass dividing the top of my tank right smack in the middle, and I'm not entirely sure how it effects the light which sits above it. The width of the glass is roughly 1 foot, 6" on each side. The fixtures would be built into a new DIY canopy, to replace the industrial hood which hangs from my ceiling now.
SinisterSOB is offline   Reply With Quote Quick reply to this message
Old 03-24-2012, 02:20 AM   #4
Hoppy
Planted Tank Guru
 
Hoppy's Avatar
 
PTrader: (74/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 18,354
Default

I don't know how good the hydroponics shop T5 lights are. I think you could get away with using 2 foot long lights, over each end of the tank, but the center of the tank would be dimmer than the areas directly under the bulbs. On the ends of the tank, you gain some intensity from light reflected off the end glass, but that isn't there for the center of the tank.
__________________
Hoppy
Hoppy is online now   Reply With Quote Quick reply to this message
Old 03-24-2012, 03:01 AM   #5
SinisterSOB
Algae Grower
 
PTrader: (0/0%)
Join Date: Mar 2012
Location: C At Hell
Posts: 25
Default

Quote:
Originally Posted by Hoppy View Post
I don't know how good the hydroponics shop T5 lights are. I think you could get away with using 2 foot long lights, over each end of the tank, but the center of the tank would be dimmer than the areas directly under the bulbs. On the ends of the tank, you gain some intensity from light reflected off the end glass, but that isn't there for the center of the tank.

Thank you for your help, Hoppy. I think if I mount the lights in the space between the middle glass and side of the tank, I'll have 6"s of room near the side of the tank, and the other edge of the light next to the thick glass in the middle. If I'm able to lower the fixture enough, I could get just below the middle panes of glass.

I took cell phone pictures, but the glare is horrendous.

Could this possibly give full coverage on the substrate with medium light intensity?

Any recommendations for lights? I went with ZooMed for my 4' industrial hood, but I'm not realy impressed with them.
SinisterSOB is offline   Reply With Quote Quick reply to this message
Old 03-24-2012, 05:02 AM   #6
plantbrain
Planted Tank Guru
 
plantbrain's Avatar
 
PTrader: (253/100%)
Join Date: Dec 2003
Location: The swamp
Posts: 13,107
Default

To deal with algae and other issue, you might use floating pennywort/water sprite etc, and Crypts on the bottom.

T8 shop lights can add more even light for peanuts. Get the Home Depot with electronic ballast and decent reflectors.
__________________
Regards,
Tom Barr
plantbrain is offline   Reply With Quote Quick reply to this message
Old 03-24-2012, 06:12 AM   #7
SinisterSOB
Algae Grower
 
PTrader: (0/0%)
Join Date: Mar 2012
Location: C At Hell
Posts: 25
Default

Quote:
Originally Posted by plantbrain View Post
To deal with algae and other issue, you might use floating pennywort/water sprite etc, and Crypts on the bottom.

T8 shop lights can add more even light for peanuts. Get the Home Depot with electronic ballast and decent reflectors.
Thanks for the advice.

I will look into the crypts, and try float plants again. The filtration (Fx5 & 2 HoB) I have seems to make it rough on anything floating, duckweed didnt do very well.

I'll check out some T8's tomorrow...Would mixing mylar with T8's provide better light than T5HOs? From the PAR vs Distance sticky, good reflectors multiply the amount of light by a great deal, but I'm still trying to wrap my head around these new concepts. Bigger and more powerful arent always best seems foreign.
SinisterSOB is offline   Reply With Quote Quick reply to this message
Old 03-24-2012, 07:06 PM   #8
Hoppy
Planted Tank Guru
 
Hoppy's Avatar
 
PTrader: (74/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 18,354
Default

Quote:
Originally Posted by SinisterSOB View Post

I'll check out some T8's tomorrow...Would mixing mylar with T8's provide better light than T5HOs?
T5HO lights give a lot more light than T8 lights. But, if you want to save money, these HD Shop Lights, http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051 are surprisingly good. People use them on 55 gallon tanks which are the same height as your tank, so you would get the same light intensity.

More, brighter, higher wattage, don't equal better with lighting, unless you actually need the extra light, for an extra high tank, for example.
__________________
Hoppy
Hoppy is online now   Reply With Quote Quick reply to this message
Old 03-24-2012, 07:44 PM   #9
SinisterSOB
Algae Grower
 
PTrader: (0/0%)
Join Date: Mar 2012
Location: C At Hell
Posts: 25
Default

Quote:
Originally Posted by Hoppy View Post
T5HO lights give a lot more light than T8 lights. But, if you want to save money, these HD Shop Lights, http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051 are surprisingly good. People use them on 55 gallon tanks which are the same height as your tank, so you would get the same light intensity.

More, brighter, higher wattage, don't equal better with lighting, unless you actually need the extra light, for an extra high tank, for example.

Awesome, thanks Hoppy and Plantbrain...Great info! Hopefully once I start my new fert regiment I'll start growing plants instead of watching them wither under high intensity lighting from my T5HO's!
SinisterSOB is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 08:00 PM.


Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright Planted Tank LLC 2012