A 2 bulb Hagen GLO light sitting on top of a standard 29 gallon tank would be very high light. That is very likely to be too much light to ever get enough CO2 in the water to keep the plants growing well, if you have fish in the tank.
I was wondering if you could tell me if I have too much light in my tank?
I currently have a 29g tank with a Hagen T5HO GLO Double bulb fixture. Standard reflectors that came with the fixture, and both bulbs are 24W 6700k.
Assuming this is a 4 foot long tank, the 2 foot T5HO light would give sufficient light on the portion of the substrate that is under the light, the middle 2-2.5 feet of the tank, with the ends being very low light. A four foot T5HO would give about the same light intensity, but over the whole length of the tank.
Hey this is in regards to the thread "Taking it serious with a 55gal."
I am so sorry to bother you with private message but i feel as if my thread will get lost in the mix, You said one t5 bulb with a good reflector and true HO ballast will be sufficient for my standard 55gal. (it was a rectangular aqueon kit), were you referring to a 4' t5 HO or 2' t5 HO? thank you very much for your time, i am just starting out and desperately need sage advice. There is a lot of information out there and it is a daunting task to weed through it.
I don't recall seeing a one bulb Catalina light fixture, but I suspect they would make one if someone wanted it. They make most, if not all of their lights to order, so customizing isn''t a big deal for them. The "solar" lights are the ones I have seen data for, so those are the ones I always refer to when I mention Catalina lights.
A 20L tank is so low, with the substrate only 10 inches or so below the top, that a T5HO light will always be too much light unless it is raised a foot or so above the top of the tank. Regular T8 lights would be a better choice for that tank.
Hoppy, I see you promote the Catalina Aquarium lights for their reflectors and was wondering if there was a specific type as I see they have single bulb "planted aquarium" fixtures and standard 2+ bulb fixtures. (They look like different reflectors so was wondering which type you tend to reference, currently need a light for a 20 long)
You could get a custom Catalina Aquarium 2 x 24 inch T5HO, made with a 10 inch wide housing, with the bulbs 7.5 inches apart. That light, sitting on top of the tank should give you about 60 micromols of PAR which would be medium to high light. When you get tired of battling algae you could raise it to 9 inches above the top of the tank and you should get about 40 micromols, which is a very good low medium level.
CO2 wont mess anything up unless you have high light and fluctuating CO2 levels. I think you will have about 30-35 micromols of PAR with no water in the tank or from about 35-40 micromols with water in the tank. (Water concentrates light and allows reflections from the glass to increase the PAR)
A couple weeks ago on my thread you posted a link to a chart showing the PAR's for CFL bulbs and noted that a PAR of 35 or below would keep me from worrying about CO2. At that time I was planning on using 14W bulbs but I ended up buying 19W bulbs. The bottoms of the round clamp light reflectors are about 17 inches from the substrate and the bulbs themselves are probably about 19. From the chart it appears this puts me at a PAR of about 35 but I thought I'd ask you to be certain. Also, I was thinking of adding a little DIY CO2 every now in then, will this mess anything up?