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Discussion Starter · #1 ·
So, I've had really good luck with the Coralife T5NO fixture on a 15 gallon (12" tall) no ferts, no cO2, 1/2 doses of excel. I suspect I just lucked into a good balance between fish and plant load. I'm growing egeria densa, valisneria spiralis, rotalla rotundifolia, echinodurus bleheri, e. barthii, and java ferns with minimal algae issues after adding some amanos and starting the excel.

I've not had the same luck on a 20 high... and have been dealing with considerably more algae problems. Seems backwards to me given the tank depth, but I also have a lower plant density to fish load ratio in this tank.

I'm about to decommission the 20 high and replace it with a 40 breeder, and would really like to replicate the successes from the 15 gallon. I'll plant heavily at the start (the 20 was started sans live plants, and never recovered) and plan to use flourite black sand as the substrate with Tom Barr's low-tech dosing regimen.

I originally thought I could get by with a 36" version of the Coralife T5NO light (2x21W), but have since become concerned about the spread. I'm just not sure that fixture will cover the full 18" front-to-back for the 40 breeder. It would be straightforward enough to just use two of the fixtures, but then I worry about too much light. Same goes for a 36" dual T5HO fixture raised above the tank... it will probably take care of the spread, but I'm afraid it will be too intense for a no CO2 setup. Plus, I really prefer the lights sitting on the glass canopy to avoid the glare.

I've studied Hoppy's charts and graphs, but I can't land on anything definitive about the spread question.

Any thoughts?

Thanks in advance.
 

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One T8 or T5 bulb can cover a 12 inch front to back tank pretty well, unless it is a very low tank. The 40 breeder tank would probably need two bulbs separated by at least 8 inches to get good coverage, without much increase in intensity over that of a single bulb. You could use 2 single T5HO bulb lights, with a very good reflectors, raised 3-4 inches above the top of the tank for around 40-50 micromols of PAR. One way to do that is to have Catalina Aquarium make a custom 2 bulb light for you, using a housing made for 6-8 bulbs so the two bulbs are widely separated.
 

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Discussion Starter · #3 ·
Thanks, Hoppy. I really appreciate your input, and willingness to answer the same question that has apparently been asked repeatedly (even though I missed it when doing a search).

On this thread (from a couple of weeks ago), you suggest that two dual bulb t5no fixtures, spaced far enough apart, might do the trick. I had considered a custom option from Catalina and your post confirmed the validity of the option, but the Coralife T5NO fixtures are readily available locally and priced right. That's not to say I mind spending the money to get the right setup.

Given my desire for "no gas", is there a significant upside to 2x39w T5HO (with plenty of spacing between them) as opposed to 4x21w T5NO accomplished with two separate fixtures? I'm thinking that the two fixtures would allow me to vary the intensity during the photo period and afford me some flexibility depending on the results I see. Perhaps I'm not seeing the bigger picture.
 

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The advantage of T5HO lights is that there are a lot of different bulbs available for it. T5NO bulbs are not available in nearly as big a variety. T5HO bulbs, with good reflectors give you more than twice the PAR of 2 T5NO bulbs, so you can more easily have too much light with the T5HO lights. Beyond that I think it is just personal preference.
 

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One T8 or T5 bulb can cover a 12 inch front to back tank pretty well, unless it is a very low tank. The 40 breeder tank would probably need two bulbs separated by at least 8 inches to get good coverage, without much increase in intensity over that of a single bulb. You could use 2 single T5HO bulb lights, with a very good reflectors, raised 3-4 inches above the top of the tank for around 40-50 micromols of PAR. One way to do that is to have Catalina Aquarium make a custom 2 bulb light for you, using a housing made for 6-8 bulbs so the two bulbs are widely separated.
can I just get 2 single bulb T5HO fixtures? I'm setting up a 40B, too.
 
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