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Discussion Starter · #1 ·
I have been planning to buy Current Nova Extreme fixtures for the following tanks (to replace the stock lighting):

28G bow 24in 2x24
29G 30in 2x24
36G bow 30in 2x24 (also considering the new Coralife T5 HO 2x31)
46G bow 36in 2x39

I want to grow low light and some moderate light plants (anubias, crypts, java fern, vals, swords and some easy stems like egeria najas and cabomba). I don't want to have to dose CO2 as I want to keep the tanks low maintenance- I'm primarily a fish person, but want to use live plants because of the benefits they provide.

I've been reading some posts and am now concerned that the fixtures I am selecting would put me into high-light range. I thought these fixtures would be barely enough for low light plants- particularly on the 36G and 46G tanks.

Would someone help me figure out what I should do?

If these fixtures put me into high light, would a shorter photo-period help?
 

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I have a 30 gallon 36x12x16 tank and tried the Current Nova Extreme T5 HO 2x39 with both the stock bulbs and geisemann bulbs. It definitely did not put me in "high light". My HC and other plants acted as if it was not enough light and did not grow low and compact. So it would probably work well for your low-mid light purposes.
 

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Based on my own experience with T5HO I'm going to say that MOST of the time T5HO will put a tank in the "moderate-to-high" light category, even at 1-2 wpg.

If you're certain you don't want to go with CO2, my recommendation would be to stick with T5NO.

Unless you're OK dosing Excel or incorporating floating plants, which are another method of light control.

Reducing photoperiods can help, but only so much.
 

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T5HO will give you high light intensity, except for really high tanks, like 30 inches or more. But, if you suspend the light fixture over the tank, so you can raise it up several inches, you can reduce the intensity back down to the low to medium range. Suspending the light fixture can look pretty good, and is easy and cheap: see http://www.plantedtank.net/forums/t...oceanic-illuminata-riparium-2.html#post910650

It really doesn't make sense to buy T5HO lights when you only want low light intensity, and are sure you won't want high intensity later. Why not just use cheap T8 fixtures or, at most, T5NO fixtures?
 

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Hoppy, would it help gryffin to run just one bulb in each of the fixtures to achieve lower intensity?

One of the bulbs on one of my Nova Extreme 36" 2x39 fixtures just burned out a few days ago but the other bulb still runs, so now one of my fixtures is a 36" 1x39w. :red_mouth
 

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A single T5HO bulb has to be about 25 inches above the substrate to give 40 micromols of PAR, which is about the top intensity to be treated as low light, or about 30 inches from the substrate to get 25 micromols, which is about the lower end of the low light range. Unless the second bulb is widely spaced from the first bulb, as much as 10 inches or so, it will just about double the PAR, raising it well above the low light range.

But, a suspended light, mounted a foot or so above the tank is best anyway, because it reduces the spread of light intensity between the substrate and water surface, and gives very uniform lighting of the substrate. Unless you really have problems with fish jumping out of the tank, an open top tank with a suspended light is the ideal setup (in my opinion, of course)
 

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Discussion Starter · #7 ·
Based on the feedback you've given me and more reading! I've come up with the following selections:

28G (18H) bowfront - 24" Coralife 2x14W T5
29G (18H) standard - 30" Coralife 2x18W T5 (1.24 wpg)
36G (21H) bowfront - 30" Current Nova Extreme 2x24W T5HO (1.33 wpg)
46G (20H) bowfront - 36" Current Nova Extreme 2x39W T5HO (1.69 wpg)

I think 29G and 36G tanks are right where they need to be.

I'm a little bit concerned that the 28G will have too little light though it does hit the minimum 1 wpg that I have seen recommended.

However, I'm most concerned about the 46G- 1.69 wpg is probably too high, my other options are 42 wpg (T5NO) which I am concerned is too low, or 96 wpg CF which is more expensive than either T5 option.

Getting a double-tube T8 fixture is more expensive than the T5's- but less expensive than the CF, but I don't think it will give me enough light on the 46G (60W max). The 30" and 24" double-tubes have the white reflectors so as well as being more $ than T5s's they probably won't work all that well.

I can't keep open top tanks because I have jumpers in all of my tanks.
 

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I wouldn't use WPG to determine low/medium/high light, especially with T5NO/T5HO lighting. WPG was developed way back for T12 lighting, which are higher wattage and lower light intensity. PAR measurements at the substrate are the most accurate.

Since all your tanks are less than 30" high I think T5NO would be your best bet for keeping low enough light that you won't need CO2 supplementation.

You also could go suspended T5HO just in case you want to do higher light later on. You should still be able to suspend the fixture above your tanks if you have glass tops. Also the glass tops would reduce the light intensity so you wouldn't have to suspend them as high.
 
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