[BrentD]

Need suggestions on lighting for a 500G planted tank. Dimensions are 10' long by 2.5' wide.

The aquarium currently has 2 large Metal Halide fixtures that use the large screw-in bulbs. Not sure of the wattage rating on them.

I have considered re-fitting with fluorescent, but to get to even 2 watts per gallon would take a LOT of fluorescent fixtures.

I'm not sure if I could consider ODNO lighting since this is in an office lobby.

Thoughts?

 

[Hoppy]

Don't even think about watts per gallon - it means less than nothing for that tank. My calculation says the tank is about 32 inches deep. One T5HO bulb gives about 25 micromols of PAR, barely enough to call "low light". But, two bulb fixtures should give about twice that, which is medium light intensity, probably all you would want in an office tank. The 30 inch front to back depth means you need about 3 of those 2 bulb fixtures spread out over the top, about 10 inches apart, which should give uniform lighting, probably with a maximum of around 75 micromols of PAR, close to being high light, and possibly too much. But raise those fixtures about 4-6 inches and that should drop the intensity back into the medium intensity range.

Since finding 10 foot long bulbs would be a big problem, if they even exist, you could use 4 foot fixtures, two end to end, with a few inches between them. That means 6 of those fixtures, each with 2 54 watt T5HO bulbs, or 12 x 54 watts, which is about 650 watts. I'm glad I don't have to pay for those.:icon_cool

 

[smp]

I'm no expert, but I would "guess" that anyone that could afford a 500gal (probably custom made, triple filtered, with self correcting water via computer controlled apparatii (sp)) aquarium, is probably not "overly" concerned about the cost of lighting. :icon_cool:

I (we) would love to see a picture of it. :drool:

 

[BrentD]

For pics, see This Thread

It's taken me over a year to finally get around to tackling the conversion.

This is an old tank. It was built in to the cabinets back when the building was bank. Probably sometime in the mid to early 80's. There are no computer controls or anything on it at the moment.

There are two water circulation loops. The first loop goes into overflow columns at the two rear corners of the long side of the tank, then down into a 2-chamber sump on each side. There is a piece of blue filter pad across the top of the bio balls in each corner and another piece of filter pad across the top of the bio-balls in the first chamber of each sump. One sump has a protein skimmer (that does not appear to be working properly) in the second chamber. A pump draws from the two sumps and sends the water back up through a pipe in each corner column to 2 positionable water jets just outside the filter columns.

The second pump draws water in from a screened riser in the middle of the tank, runs it through what appears to be a carbon canister and then back up to a T fitting in the middle of the rear wall of the tank. The T fitting used to have sections of PVC pipe with holes drilled in it that ran along each side of the tank to provide an upward current, but those pipes have been removed so the water just returns back out where it is. Makes a mess of the filter sand on each side of the T. I'm not sure whether I should put those hole bars back or just hardscape around that return to direct the flow off the substrate. I'm going to have to hardscape around the rise in the center of the tank anyway.

Now, in the future, I plan on adding controls to maintain lighting, water changes, PH, possibly even food and fertilizers, but I will have to build all the controls myself. The boss is changing to fresh water because the salt water is "too expensive to maintain". I'm not sure if he realizes how much the conversion is going to cost, but he's given me pretty much free reign to do it as I see fit. He knows he can trust me to get stuff done in a way that usually achieves a decent balance between cost and "the best way possible". The goals for a the aquarium is balance minimal maintenance with best appearance at a reasonable cost.

 

[lauraleellbp]

Don't even think about watts per gallon - it means less than nothing for that tank. My calculation says the tank is about 32 inches deep. One T5HO bulb gives about 25 micromols of PAR, barely enough to call "low light". But, two bulb fixtures should give about twice that, which is medium light intensity, probably all you would want in an office tank. The 30 inch front to back depth means you need about 3 of those 2 bulb fixtures spread out over the top, about 10 inches apart, which should give uniform lighting, probably with a maximum of around 75 micromols of PAR, close to being high light, and possibly too much. But raise those fixtures about 4-6 inches and that should drop the intensity back into the medium intensity range.

Since finding 10 foot long bulbs would be a big problem, if they even exist, you could use 4 foot fixtures, two end to end, with a few inches between them. That means 6 of those fixtures, each with 2 54 watt T5HO bulbs, or 12 x 54 watts, which is about 650 watts. I'm glad I don't have to pay for those.:icon_cool

I got lost somewhere, Hoppy... why wouldn't 2 end-to-end 4' fixtures each with 2x54 T5HO be enough?

Though if you could rig it to have space between the bulbs (perhaps 4 1 bulb fixtures in 2 rows along the tank) that would be better light coverage.

If you want to go a REALLY easy route, you could go with 2x 4' fixtures with 3x T8 bulbs, and then just stick with super-easy plants- Java ferns, mosses, Anubias, Crypts, Swords, Vals... with a really nice big driftwood hardscape, and still have a really nice-looking planted tank.

 

[GTR]

I think the estimated 32" depth is why more fixtures are suggested.

SteveU

 

[lauraleellbp]

Right, but if the goal is to set up a low tech/low maintanance tank, then 32"-36" isn't all that high for a T5HO fixture to sit up from substrate level.

EDIT- I think I'm confused about which dimensions are height vs depth...

Brent, could you confirm those dimensions?

 

[GTR]

2.5' wide would also be hard to light with 2 bulbs in the same fixture.

 

[BrentD]

Brent, could you confirm those dimensions?

The tank is 10' long by 2.5' front to back by 2.5' tall.

 

[BrentD]

Would 2 of these fixtures end to end across the length of the aquarium be sufficient?

 

[lauraleellbp]

They would be too MUCH light running all 8 bulbs... and there's only 2 switches running 4 bulbs @ so I don't think that fixture would work. Even 4 bulbs would definitely put you in the range of needing pressurized CO2 setups (probably 2 of them since this tank is so long). 3 T5HO bulbs may even need that...

The issue is that Hoppy is right, since the tank is 30" wide AND 30" tall, you're going to need 3 bulbs spaced out to get light in both the front and the back of the tank.

How handy are you with DIY electrical?

I'm starting to think that 2 DIY fixtures with 3 well-spaced T5NO (instead of T5HO) bulbs may be a really good way to go... and would probably be fairly inexpensive if you could build them yourself. Or find some retrofit kits and just find something to mount them in/on.

 

[BrentD]

How handy are you with DIY electrical?

I'm starting to think that 2 DIY fixtures with 3 well-spaced T5NO (instead of T5HO) bulbs may be a really good way to go... and would probably be fairly inexpensive if you could build them yourself. Or find some retrofit kits and just find something to mount them in/on.

I am the DIY Master, be it plumbing, electrical, mechanical, you name it. From what I'm seeing, it looks like T5 and T8 bulbs both use the same end connectors. If that is correct, I'll just stop by the fluorescent lamp repair aisle in Lowes or Home Depot and get the connectors, then order the correct ballasts and build my own fixtures.

I'm also planning on automating water changes, fertilizer injection, etc. I will probably eventually be adding either a pressurized CO2 system or a large DIY system.

My thinking on the CO2 is this... Remove the carbon canister in the second pump loop and replace it with a CO2 reactor, then put the hole bars back into the T fitting so the system will flow the CO2 infused water up the entire length of the back wall of the aquarium... Does that sound like it would work OK? Not sure if I want to use the sump chambers for the sump chambers for dosing the ferts or if I want to plumb them into this second flow loop...

I guess this is going a bit beyond the scope of the lighting forum...

 

[GTR]

Does is already have a canopy?

If you plan to DIY the lights I'd still suggest you buy the reflectors from a hobby source to make best use of the light.

SteveU

 

[BrentD]

Does is already have a canopy?

If you plan to DIY the lights I'd still suggest you buy the reflectors from a hobby source to make best use of the light.

SteveU

The aquarium is currently lit by two "pods" supported by bent pieces of electrical conduit. Each pod contains a socket for a single-end metal halide light. You can see the pods in the picture below. The pod on the right is sort of falling apart.

I have several old 4' shop lights with dead ballasts out in my garage that I can salvage reflectors from.

 

[jjp2]

Based on how the tank is situated, you could use 4 - 5 75 watt MH pendants or build a canopy for the T5HO. Looking at the dimensions and the pictures in the other thread, 4 T5HO spread out over the 30 inches across the tank should pentretate the 30 inch deep tank and should give a medium light level. I would go with the 60 inch bulbs, so you'd need 4 of retrofit kits for the canopy.

 

[GTR]

I have several old 4' shop lights with dead ballasts out in my garage that I can salvage reflectors from.

Thanks for the visual, makes it a little easier.

Most shop lights I've seen are nothing more than a flat metal behind the bulbs. I good reflector will wrap each bulb individually and give you the most light per bulb.

If it were me I'd consider using the supports you have and fabricate a box from lightweight materials to house T5 bulbs. It could be suspended over the top of the tank. Of course this idea assumes the current supports you have can handle the load. An enclosure 10' x 30" is going to be heavy regardless of the materials used. Looks like it's high enough that the top wouldn't need to be skinned, just cross bracing for structural support.

SteveU

 

[BrentD]

If it were me I'd consider using the supports you have and fabricate a box from lightweight materials to house T5 bulbs. It could be suspended over the top of the tank. Of course this idea assumes the current supports you have can handle the load. An enclosure 10' x 30" is going to be heavy regardless of the materials used. Looks like it's high enough that the top wouldn't need to be skinned, just cross bracing for structural support.

SteveU

The current supports are pretty much crap. It looks like they built the whole tank, blew all their budget, got to the end and somebody said "Hey boss, what are we supposed to do with them lights?" So they ran out side, grabbed a couple of pieces of 1/2" metal conduit, screwed them to the back of the tank, bent them roughly to shape and secured the lights to them with bailing wire. (And yes, the lights are indeed secured with bailing wire if you look at the fixtures from the top).

I think either making a more aesthetically pleasing support structure or hanging the light box from the ceiling will be a big plus.