Average WPG???

[Feynman]

I have a 38 gallon tank and I was hoping to get about 2.0 - 2.25 [acronym:4461375666="Watts Per Gallon"]wpg[/acronym:4461375666] with [acronym:4461375666="Power compact fluorescent"]PC[/acronym:4461375666] lighting. I am thinking about the Coralife Daylight 6700k 65W lights. I obviously can't get the 2.0 - 2.25 range I'm looking for with 1 bulb, and 2 is too much.

If I buy the 2x65W fixture, can I average 2.0 [acronym:4461375666="Watts Per Gallon"]wpg[/acronym:4461375666]? For example... could I turn on one light on day 1, turn on both lights on day 2, etc... and therefore get an average [acronym:4461375666="Watts Per Gallon"]wpg[/acronym:4461375666] of about 2.5 or so?

With this lighting scheme will I need [acronym:4461375666="Carbon dioxide"]CO2[/acronym:4461375666]? I was thinking about getting the Dupla [acronym:4461375666="Carbon dioxide"]CO2[/acronym:4461375666] Diffusor. Any thoughts?

[acronym:4461375666="Thanks in Advance"]TIA[/acronym:4461375666]

[Wizzard~Of~Ozz]

I have 3 [acronym:9daf72f80a="Normal Output Fluorescents"]NO[/acronym:9daf72f80a] flourescents on my tank, I have one that comes on around 10am (PowerGlo) , the other 2 (Flora Glo and Powerglo) come on around 12:30, the turn off around 8pm, the first powerglo turns off around 9:30pm.

Perhaps that would be better for you, since it would give them a closer to real world atmosphere.

As for your question, I'm not sure if an average is really accurate, I'ld just reduce the time the second light is on. (1 bulb for 10 hours, the other for 5 hours in the middle)

a better gardener will have to answer the [acronym:9daf72f80a="Watts Per Gallon"]WPG[/acronym:9daf72f80a] question, since I have a brown thumb my answer probably wouldn't be best.

[travis simonson]

I agree with Wizard on this one. You should always keep your photoperiod consistent from day to day so that your plants can become acclimated to it. And it will work best if you just run full intensity for about 5-6 hours a day, with the remaining time at half lighting. This is similar to the way Takashi Amano runs his tanks with [acronym:90ec1a6dcb="Metal halide light"]MH[/acronym:90ec1a6dcb] lighting and it looks like it works pretty well for him

I would recommend [acronym:90ec1a6dcb="Carbon dioxide"]CO2[/acronym:90ec1a6dcb] for any planted tank above 2 [acronym:90ec1a6dcb="Watts Per Gallon"]wpg[/acronym:90ec1a6dcb]. It just reduces your algae issues a lot. I've never used a Dupla diffuser but I know they're a good company. Hopefully someone else can help out with that one

[TankGirl]

What kind of plants do you want to grow, and what is your tap water [acronym:fe74c4ec84="Carbonate Hardness"]KH[/acronym:fe74c4ec84]?

These are the first things to know. You can grow a very nice assortment of relatively low light plants with a single 65w [acronym:fe74c4ec84="Power compact fluorescent"]PC[/acronym:fe74c4ec84] fixture. You will likely not have algae issues and then you won't need [acronym:fe74c4ec84="Carbon dioxide"]CO2[/acronym:fe74c4ec84] if you are not sure you want to take that step.

If you do want to go for higher light plants and [acronym:fe74c4ec84="Carbon dioxide"]CO2[/acronym:fe74c4ec84], then you'll need to have [acronym:fe74c4ec84="Carbonate Hardness"]KH[/acronym:fe74c4ec84] of 3-4 degrees for a stable pH, which will be brought down from where it is now by the [acronym:fe74c4ec84="Carbon dioxide"]CO2[/acronym:fe74c4ec84]. This becomes a much higher-maintenance tank, and you need to be ready for this. You'll be dosing ferts and testing water params much more often than you would without high light and [acronym:fe74c4ec84="Carbon dioxide"]CO2[/acronym:fe74c4ec84].

Then you can handle it as Wizzard suggests with the highest intensity period in the middle of the day, flanked by lower intensity periods in the AM and PM.

This is a tall tank, is it not? I do not know how this impacts your [acronym:fe74c4ec84="Watts Per Gallon"]WPG[/acronym:fe74c4ec84] (soon we'll quit using that term, it's on its way out like "inches of fish/[acronym:fe74c4ec84="Gallon"]gal[/acronym:fe74c4ec84]") because the light has to get all the way to the bottom. Malkore might have something to share about that.

[Feynman]

Thanks for the replies, the high intensity for a shorter time period really does make the most sense.

I don't know my [acronym:27d85b474c="Carbonate Hardness"]KH[/acronym:27d85b474c] right now. I'll have to go buy a test for that. I went ahead and got the 2x65W fixture thinking that it at least gives me more choices and who knows what I'll want to be doing in the future.

I don't mind doing the testing and I'm really thinking I may want to go ahead with the [acronym:27d85b474c="Carbon dioxide"]CO2[/acronym:27d85b474c]. I envision a highly planted tank. I was thinking some Anubis (sp?) and things like that which if I remember are relatively low light, but I also want some foreground "carpeting" type plants and it seems like those tend to require more light.

The Dupla diffusor would be enough [acronym:27d85b474c="Carbon dioxide"]CO2[/acronym:27d85b474c] then? The description says its good for up to 50 gallons. Does pressurized [acronym:27d85b474c="Carbon dioxide"]CO2[/acronym:27d85b474c] only apply to larger tanks?

I don't know the definition of "tall tank" but my tank's measurements are 24L x 18w x 18h. So probably not since most tanks are 18 high right?

[TankGirl]

Nope, that's not too terribly tall and will make it easier. If you leave all of the lights on for any amount of time you will really need [acronym:1165645c65="Carbon dioxide"]CO2[/acronym:1165645c65], so find out your [acronym:1165645c65="Carbonate Hardness"]KH[/acronym:1165645c65] and go from there. Anubias will probably do best in this tank if it is partially in the shade, at least my experience has been such. Hopefully you'll have other plants to provide that!

Dupla makes several types of diffusers - some of them pricey and others a glorified air stone. Which one were you interested in?

[Feynman]

The Dupla product I'm looking at is this one from aquariumplants.com

http://www.aquariumplants.com/cgi-bin/cart/pr008.html

[Feynman]

So... why doesn't anyone use this kind of [acronym:dd7b64d26b="Carbon dioxide"]CO2[/acronym:dd7b64d26b] device? I don't want to waste my money on something that doesn't work. What should I be getting instead?

[TankGirl]

It may work fine - I don't know, but I prefer a forced diffuser, using pumped water in a container that breaks the bubbles into tiny particles, so you get as little as possible of the [acronym:de66dc873b="Carbon dioxide"]CO2[/acronym:de66dc873b] rising to the surface and being wasted in the atmosphere.

Some people plumb their [acronym:de66dc873b="Carbon dioxide"]CO2[/acronym:de66dc873b] to feed into their canister filter intake (debate on whether or not this damages the filter itself) or you can plumb it into the outflow of your filter.

I have one of these, but everyone has a different favorite way of diffusing:

[malkore]

That's basically a passive reactor. Works well in tanks around 20 gallons, but I disagree with the manufacturer's claim of 50 gallons. To get it to work well on a 50gallon tank, you'd need to position it under your canister filter intake so the tiny bubbles are sucked into the filter, and fully dissolved.

Also, these sintered glass discs have to be cleaned very frequently, as they are so fine they plug up rather easily.

For a tank your size, you'd really want either an in-line reactor on your canister's return line, or something like a Vortex reactor inside the tank.
In line reactors are like the AquaMedic