Lighting question

[dannylc]

Hello

I am setting up a planted 120cmx60cmx76cm (lwh), what I would like to know is your opinion on my lighting idea.

I will be using x4 ordinary home style pendant lights equally spread over the tank, my bulb idea is this,

The two end bulbs 6500k and the two centre bulbs 4000k total 21k, my idea is to have all 4 on for say 12hrs in the day ( 8am-7-8pm ), dropping down to the 2 4000k in the evening and night for a more subtle lighting ( 7-8pm - 12-1am )

Would this be two much and would I be better off with say x2 2700k and x2 4000k?

Thanks
Danny

[jcgd]

Not Sure what you mean. Even if you change the colour temperature you will still have 4 bulbs. I would guess the 6500k would look best. It might look okay mixed with the 4000k but it might be very yellow too.

What bulbs are you using? Led?

[dannylc]

Originally Posted by jcgd

Not Sure what you mean. Even if you change the colour temperature you will still have 4 bulbs. I would guess the 6500k would look best. It might look okay mixed with the 4000k but it might be very yellow too.

What bulbs are you using? Led?

Hello,

I will be using 15w ( 60w equiv ) 6500k spiral energy savers, the sort of bulbs used in photography.

They will be on pendant lights ( hanging from the ceiling ) over the open top of the tank with aluminium shades that will direct all of the light down into the tank.

With the shade size I am thinking they will be about 30cm above the surface to ensure the light is directed down into the tank only and no overspill of light from front or back but I need to have the tank in place to check that out.

Just wondering if 4 6500k bulbs would be to much?

This is a project I will be starting this weekend

[Hoppy]

You won't have enough light. If you lower the lights to about 3 cm above the top of the tank, and use 23-25 watt bulbs, you should get good low light, around 20-25 micromols of PAR. If you use 5, instead of 4 pendants, you might get more uniform light. The color temperature of the bulbs affects nothing except how the tank looks. Most of us like 6500K bulbs better than any of the other common bulbs.

[dannylc]

Do you think then I would be better off with x6 lights? the light end of the shade is 25cm so could have 6 if need be?

[dannylc]

A very quick mock up of how it will be placed,

[dannylc]

I will be using dimmable bulbs so at night can lower the light, I could use x6 20w ( 6500k ) if you think that would be better to give a full daylight lighting when on full rather than a dull effect.

[xmas_one]

Are you trying to grow plants? 15w spiral bulbs aren't going to cut it over a tank that size. If you're stuck on hanging pendants, I'd suggest you go with three 70w MH.

[dannylc]

Hmm, would like to grow a fair few but not a seriously planted tank. I have always had malawi's but fancy a change, I would be sticking with the lower light requirement plants and only really want the lighting to create the white daylight affect for decorative purposes more than growing but to still have some benefit to the plants.

Also as it will be an open tank I would like to have some fairy moss or pennywort or other floating plant.

[PlantedRich]

Humm! I think there may be some confusion on the ratings.

"The two end bulbs 6500k and the two centre bulbs 4000k total 21k, my idea is to have all 4 on for say 12hrs in the day ( 8am-7-8pm ), dropping down to the 2 4000k in the evening and night for a more subtle lighting ( 7-8pm - 12-1am )"

When you say this, I think you may be confusing the Kelvin rating with a number that rates the AMOUNT of light. Kelving is an attempt to rate the frequency of the light bulb. It means you get more red at lower ratings and more blue as you go higher. You can't get higher K rated light by adding more of the same. Two 6500 K bulbs still give 6500 k light. Maybe some more checking on Kelvin rating is needed---or maybe it's me that's confused!

[dannylc]

Ahha, Ok.

I know 6500k is the rating of choice for most planted tanks, I would like to have the bright white look to the tank so that is why I will be using 4 or 6 to evenly light the tank.

Do you think they would do that and will 6500k penetrate deep enough through the water to be of benefit to plants in the substrate?

It looks like the lights will be about 6" above the surface so approx 36" above the substrate, will this be to close for floating plants and cook them?

[MVA]

I am using similar set up for 40 gal (24 inches tall). I have 2 23watt 6500k spiral full spectrum bulbs. Visually the tank is very bright (but i still think I am in the lower light category). There are only two large amazon swords and bunch of very well growing salvinia minima. Lights are about an inch above the water, (no one got burned yet).

Tank is new and I am still figuring out optimal set up, but there is very little material about regular spiral bulb use for moderately planted tanks.

Also for the people on super low budget idea of $6 per clip on fixture + $5 per bulb as oppose to >$100 for t5HO fixture may be more appealing. (effective?)

[PlantedRich]

When cost is an issue (and when is it not?) , I would look at this another way. Go away from changing the Kelvin rating. I would use 6500K. I then go for changing the number of bulbs, the wattage of the bulbs and the distance from the plants, to get the right amount of light. Kelvin is a way to describe the "color" of the light rather than the strength.
I use several tanks with common CFL twisty bulbs as I had no idea of what I needed when starting. I have wooden covers on my tanks so I can hide ugly things like DIY bulb holders. It gives me a way to easily move and change the lighting without needing new expensive items like fixtures. Once I determine better what lighting I like and what my plants need, I can then go for a more permanent solution.
I used these for quite some time and found they did the job very cheaply.
About $2 for the bulb, $2 for the bulbholder, and $1 for the cord plus scrap wood.


It gave me a cheap, easy way to sort out some of the questions I had. I promise to do better in the future but I still have these on one tank that I have not changed out.

[MVA]

Agreed, before investing must know for sure what you need. But that takes a while to figure out.

Also not sure why people add kelvins together? Isn't that just color of light. If you need the best color for plants think in range 430nm (blueish) and 680 (redish). Yellow and green are the least needed.

[Steve001]

Originally Posted by MVA

(redish). Yellow and green are the least needed.

True. But having output in that region makes the light and the tanks interior appear bright. Which is what most of us prefer.