# 3 or 4 bulbs T5HO - 90gal



## Skizhx (Oct 12, 2010)

I'm looking to purchase a Catalina fixture (so you know what the reflectors will be like).

The tank is a 90gal (48w x 18l x 24h). 

The catalina fixtures have two chords, so I plan to be running 2 bulbs throughout the day with a midday blast of either an additional 1 or 2 bulbs.

I'm not completely familiar with running T5HO though, and I've found mixed opinions on whether to go with the 3 or 4 bulb fixtures. I've seen some suggestions that even 2 bulbs on their own would be fine for most/all tanks.

I've looked over Hoppy's updated post on PAR and lighting, but the difference between ~50 and ~60 micromoles doesn't mean a whole lot to me in a practical sense, except that they are both within the realm of what he defines as "high light".

R. Macrandra is probably going the be the most light-demanding plant in the tank. The lowest foreground plant will be downoi.

I will be running pressurized CO2.

Really appreciate any advice!


----------



## niko (Jan 28, 2004)

Get 4. And make sure each bulb has its own reflector. it would be best if the reflector is attached to the bulb so you can rotate slightly around the bulb and direct the light where you want it. 

The light will be more than enough for a 90 gallon. You will have to have a midday burst of strong light (all 4 bulbs). Running all 4 bulbs all the time makes for a high speed tank. If that's what you want you will have it. 

Also make sure that you get good bulbs. I suggest Giesemann Midday. PAR is not everything. There is something important in the spectrum too. You can have a wide spectrum and not that much PAR and plants will be just fine.


----------



## Skizhx (Oct 12, 2010)

Thanks Niko, appreciate the input.

Individual reflectors for the bulbs, absolutely. Not sure about rotating the reflectors though. I understand they'll do custom requests, so it might not hurt to ask, but I'm not holding my breath.

Speeding up the tank unnecessarily is unappealing to me. However, some plants really look their best when given plenty of light. Just hoping to find a nice balance with the midday cycle. 

I was mostly concerned that 4 bulbs would be going overboard. The shipping on all the fixtures is the same for me. I'm also liking the flexibility I'd get from having 4 fixtures (I don't think there's anything stopping me from only running 3 bulbs in it if I find running all 4 problematic).

Now the agony of waiting for a new toy... For my bigger toy...


----------



## niko (Jan 28, 2004)

Keep in mind that at 24 inches of depth even 4 bulbs are not going to fry eggs on the bottom of the tank. Yes, the light will be strong enough for any plant you want to grow. But the PAR will be about 70 on the bottom. If you decide to raise the fixture some inches above the tank then you definitely go into mid or low PAR.

Also remember that plants seriously shade each other and that PAR is a little higher by the glass because of reflection. My point is - the intensity of the light really depends on quite a few things. That's why it is good to have a very flexible light fixture that allows you adjustments. Definitely the first thing is to get enough light and start from there. So 4 bulbs it is.


----------



## TropTrea (Jan 10, 2014)

On the subject of getting 4 blb fixture and only running three bulbs in it is something that you need to be very cautious with. Dependent on the ballast they use most fixtures are running ballasts that are designed to run a pair of bulbs. If you do not have a pair of bulbs in there running they will not fire. However some fixtures do run individual ballasts for each bulb so you need to check that out.

From my experience in the past 3 Bulbs will give you more than enough light to grow most anything considering you have 54 watt bulbs rather than 40 watt bulbs like in a standard T-8 or T-12 fixture. But this is [provided you have a fixture with quality individual reflectors as well as your quality bulbs. I have found a big difference in light output between brands years ago especially when your look at specialized aquarium bulbs compared to standard lighting bulbs.


----------



## Zapins (Jul 28, 2004)

I'd go with 4x54w T5HO. That is what I have on my 90g tank and it works very nicely. Much better than the 2x55 watt PC lights I had on it before. 

Also, my fixtures have individual reflectors around the bulbs. I bought my fixture from ebay for about $130 including the bulbs and shipping. It is one of those enameled hydroponics T5HO fixtures, cheaper and better designed than many aquarium brand lights.


----------

