What would you do? Thanks for the help. With update.

[lljdma06]

Never mind about the lumens then. And I thought I was being all smart with the calculations. I don't have a PAR meter, I'll restructure my question with WPG.

Which is better?

A. 28W of T5 over 36g

B. 30W of T8 over 36g

I know both are very low light. The plants would be picked accordingly. The T8s have better spread. The T5s have more umph.

 

[Themuleous]

Re: What would you do? Reducing the lighting in my 36g corner b

Would think the cheapest option would be to put back in the stock light that came with the tank?

Sam

 

[lljdma06]

Re: What would you do? Reducing the lighting in my 36g corner b

That is what I'm thinking, which is so funny. Just buy some better bulbs.

llj

 

[ceg4048]

Re: What would you do? Reducing the lighting in my 36g corner b

Hi,
Lumen values are of no relevance to plants. This is not a viable parameter. Although wpg is itself imprecise, it's the best we can do if we have no access to a PAR meter. On a 36 gallon tank it's rather easy to determine that 130 watts, almost 4wpg is a lot.

Cheers,

 

[lljdma06]

Re: What would you do? Reducing the lighting in my 36g corner b

Yes, I know that 130W over 36g is about 4WPG. I know how to calculate WPG. I don't want to raise lighting, but lower it. I changed the question in the first post to reflect WPG, sorry for my error. I was using out-of-date information. Typical of someone who isn't into Planted tank technology but still keeps planted tanks.

llj

 

[GreenNeedle]

Re: What would you do? Plan A or B, simplified

Are we talking 2 x T8s versus 1 T5HO? If so the T8s would be better IMO

If it is 2 x T8s versus 2 x T5 then the T5s would be better. Same if it is 1 T8 v 1 T5

AC

 

[lljdma06]

Re: What would you do? Plan A or B, simplified

It is 2 x15W T8 vs 2x 14W regular output T5. No HO. Too poor for that. At least I think they are regular output. The T5 fixture wasn't that expensive.

The T8s would give .83WPG. The T5s would give .77WPG. The tank is 21" deep, but probably more like an 18" difference once the substrate is revamped. I don't think the depth would make much of a difference and the low-growing plants would most probably be crypts with areas of bare substrate. Not trying to grow glosso here!

The T5s have a reflector, a big plus, despite the lower WPG. I figure the T5s would almost be like 1WPG of T8, unless I'm completely wrong. Whereas, the T8s might not actually be at .83WPG because of the magnetic/electric ballast. I also would most definitely have to purchase new bulbs for the T8 fixture. I actually have all the equipment for the T5 fixture, including some older bulbs, and the T5 bulbs are actually a little cheaper than the correct T8 bulbs. The stock bulbs for the T8 fixture are pretty lousy. My only concern about the tank is that the T5 bulbs are rather close together and I'm thinking a bit about spread. What I may do is compare the two and look at the results. I can get a general idea from the stock lighting in the T8 fixture.

What do you think?

llj

 

[swackett]

Re: What would you do? Plan A or B, simplified

The WPG rule of thumb is a bit misleading, it was originally used for T12 lamps. T8 lamps produce more light than an Equivalent wattage T12 and T5 lamps produce more light than an Equivalent wattage T8. Even though you said the T5 have lower wpg than the T8, the T5's will be brighter and thus they will also penetrate deeper into the tank. As the T5 also have reflectors, this can also add another 10-15% on top of the lamp output.

If you intend to grow crypts, java fern, and nubias, etc then the IMO the T8's would be fine.

 

[aaronnorth]

Re: What would you do? Plan A or B, simplified

The WPG rule of thumb is a bit misleading, it was originally used for T12 lamps. T8 lamps produce more light than an Equivalent wattage T12 and T5 lamps produce more light than an Equivalent wattage T8. Even though you said the T5 have lower wpg than the T8, the T5's will be brighter and thus they will also penetrate deeper into the tank. As the T5 also have reflectors, this can also add another 10-15% on top of the lamp output.

If you intend to grow crypts, java fern, and nubias, etc then the IMO the T8's would be fine.

WPG is calculated providing you have reflectors. If you dont have reflectors then it will be lower. You can just simply add a reflector then say the tube will have 10% higher output - it doesnt work like that unless i am missing something?

The T5 will be slightly higher tech, but either way you go wont make much difference

 

[George Farmer]

Re: What would you do? Plan A or B, simplified

If possible, try them both out and see what looks best for you.

The plants won't be too fussed either way....

 

[lljdma06]

Re: What would you do? Plan A or B, simplified

The WPG rule of thumb is a bit misleading, it was originally used for T12 lamps. T8 lamps produce more light than an Equivalent wattage T12 and T5 lamps produce more light than an Equivalent wattage T8. Even though you said the T5 have lower wpg than the T8, the T5's will be brighter and thus they will also penetrate deeper into the tank. As the T5 also have reflectors, this can also add another 10-15% on top of the lamp output.

If you intend to grow crypts, java fern, and nubias, etc then the IMO the T8's would be fine.

Yeah, I know WPG is misleading and only a loose guideline, this is what I tell people all the time in my forum, but unless you want to lend me your PAR meter, it's what I've got to work with. Thank you for pointing it out, though.

WPG is calculated providing you have reflectors. If you dont have reflectors then it will be lower. You can just simply add a reflector then say the tube will have 10% higher output - it doesnt work like that unless i am missing something?

The T5 will be slightly higher tech, but either way you go wont make much difference

Oooooo, slightly higher tech. The prospect is so exciting.

If possible, try them both out and see what looks best for you.
The plants won't be too fussed either way....

That is my inclination, but the more I think about it, I think the T5s will be cheaper in the long run. No reflector to purchase and the bulbs are cheaper than the T8 bulbs I want. I'm really just going to put mosses, crypts, swords, anubias, and bolbitis. I want the pretty new mosses too! The big change is with the substrate and the lower light. I really like the sand I put in my other aquariums and I want a sand cap for this tank too. The original gravel bed isn't especially deep, like 1-1.5", so I can easily cover that with a cap of sand and not worry too much about mixing or sinking. As long as I have more sand than gravel, I'll be fine.

Thanks for helping out everyone. I think I've made my decision.

llj

 

[Joecoral]

Re: What would you do? Plan A or B, simplified

It is 2 x15W T8 vs 2x 14W regular output T5. No HO. Too poor for that. At least I think they are regular output. The T5 fixture wasn't that expensive.

All T5's are HO (or at least that's how I understand it..... :? )

 

[GreenNeedle]

Re: What would you do? Plan A or B, simplified

Nope. If all T5s were HO there would be no such thing as HO

There are T8(NO-Normal output) and T8HO just as there are T5(NO) and T5HO

Like I put on the previous post the 863/849mm T5 is 21W whereas the HO version is 39W.

T5HO is basically a T5 overdriven but obviously there other things done to make it safe to overdrive..

AC

 

[lljdma06]

Re: What would you do? Update!

I tried all three of them out.

The 65W CF bulb I already had was brightest, but quite close was the 28W T5. Dimmest was the T8 fixture. I liked the look of the T5s best, so I went with them. Rescaped the tank and added the new wood and plants. Will probablly start a journal.

Again, thanks for the advice.

 

[Joecoral]

I learned something new then, never knew that before

 

[lljdma06]

Glad you were able to learn something. The T5s look great.