I have a 75 gallon aquarium with 2 ge plant and aquarium 40 watt 4ft flourescent bulbs. Is this enough light or do I need more for swords, sags, and possibly a random high light plant I see at the fish store and decide to try. I know WPG don't really work because some bulbs produce more lumens per watt than others. Also some bulbs make more usable light than others so how do I figure out how many bulbs I need?

I generally tell people the same thing: first of all, start with a good substrate. You want the plants to be well fed and to have something rich to root in.. I personally recommend and love Red Sea Flora Base. Secondly, add CO2.. you don't need a fancy setup, but those might make life easier, if you can afford it.. Otherwise, do the DIY method using a 2 liter soda bottle, some tubing, water, sugar, yeast and do buy yourself a $5 glass/ceramic diffuser (you can even order these on ebay).. I say try buying any of those plants and plant them in this setup and I guarantee you will be amazed at the results. You will get much better results with a good, rich substrate and CO2 injection than without it, even with your current lighting...

Are you saying I have enough light? I thought I would need to buy two more bulbs. Would adding a little more light be bad?

I have a clay substrate with pool filter sand on top. How much would DIY co2 cost for a 75 gallon?

Good morning Leopard...

You have a bit more than 1 watt of light per gallon of tank size. 1 to 2 watts of light per gallon will grow most aquatic plants. The recommended bulb is a 6500 K, because it best mimics natural daylight.

You'll need 3 to 5 watts per gallon to grow the more demanding plants that require strong to bright light.

I use 6500 K, 32 watt, T8s in my tanks and the plants grow very well.

B

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Low Tech Water Building Keeper

Forget lumens. WPG works for T8 bulbs but doesn't real well for anything else. Lights like T5HOs are much more efficient and some can produce 4 times their rated wattage. To give an example, I have only 108 watts of T5HO on my 75 and am in the low end of high light.

I forgot to mention I have T12s.

Is there a cheap plant that I could get at most fish/pet stores, that would need high light, I could get to test how much light I have?

I want to have enough light so that I can grow most plants but not so much light that lots of co2 and other fertilizers are needed. I could make a cheap DIY co2 system if it would really help.

It's not the wattage nor lumens so much as the Kelvins that need to be considered. 6700K is what most plants will thrive under. Going up to 10,000K is going to be called for when ya have a very deep tank or very demanding plants. (Baby tears for instance).
CO2?.. me, I personally think that that is nothing more than steroids for plants. Me?... I put down about 1.5 inches of cooked potting soil.. Ensure there are NO ADDITIVES to the soil. then cover it with 1.25 - 1.5 inches of pool filter sand. I'm constantly harvesting Vals, Sags, various stem plants.. and have moderate success (no kills just not much reproduction) of Crypts. Oh.. the Amazon swords reward me monthly with a new 4-5 inch plant. Bill in Va.

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12 Tanks, 900 gallons. Discus/Angels/Malawi/Lake Victorias. Just added a 135 & 2 - 29's..

Hello again Leo...

There are inexpensive plants at PetCo. Not those in the "growing tubes", some of those aren't aquatic plants. Check the tanks. Many times PetCo runs a special on actual aquatic plants for just a few dollars each. Most of those will grow in moderate light. I picked up some Water wisteria last week. Thought it was more a strong light plant, but have it closer to the light source and it's doing surprisingly well and my tanks have less than a watt of light per gallon.

Can't help with the CO2. I'm strictly low light and low tech.

B

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Low Tech Water Building Keeper

Is T8 really well for aquariums growth ? or is there a better results under LED lights ?

I think it depends on the exact two lights you're comparing. If you get low quality LEDs and high quality T8s the T8s would be better but I think good LEDs are better than good T8s.

Do T8s have high par output ? Do you have the test results on T8 and LEDs ?
I am not familiar with T8s , I guess they offer Uv for aquariums , is it right ?
T8s can not be customized as aquariums' needs , but LEDs can do that

I think the biggest factor holding me back from LEDs is the cost. Yes the low power consumption and high PAR values make them attractive, but any of the quality LED fixtures available here in the US with sufficient research and customer reviews to make them a solid investment are quite expensive. The only LED fixture my local fish store carries is nearly $250 for a 48" fixture.

Au contraire, a good 48" fixture with a 6700K T8 bulb would cost MAYBE $40.

There's also no good research on the effective lifetime of an LED fixture, whether the light quality wears down over time with continuous usage, etc.

And to be frank, I've heard from several sources that there are really only three or four good LED manufacturers, and the majority of the advertisements I see from places like China don't have any good supporting research or customer reviews on their websites.

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Officially fishless until after the move....tune in later for details!

T8s and T12s are very similar, both using the same socket (G13 bipin).. It's old technology - it's been around since the 1930s! For aquarium use, I did use T12 lamps; my favorites had internal reflectors and they worked well, but because I found a more powerful, efficient and longer lasting bulb, the T5HO, I switched fixtures. The T5HO bulbs allow me to grow more light-demanding plants without the cost of a metal halide system.

The upfront cost for LED (light emitting diode) fixtures is still too high.. I can buy complete LED circuits and create my very own fixture at a much smaller fraction of the cost of some of the LED aquarium fixtures I've seen.. The main advantage of LED has nothing to do with the type of light it emits; the long term savings from an LED fixture does make sense, since you don't need to buy replacement bulbs/lamps every six months as you would for T8 or T12.

Another good option, still better than LED, is the Compact fluorescent (CFL). If I didn't use T5HO, I would use CFLs.

How much does a CFL cost in USA , What price for LED fixture , also the cost for a T5HO ?
Who are the three or four good LED manufacturers ?

You can also choose LED strips.May be 60CM long is good!

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Love me love my aquariums.