Ok, I give up. You people are always saying that you have so many watts per gal but I want to know if you just add up your bulb wattage and put it over your tank size? Or is there something different you need to do to get the number?
How to I calculate the amount of light in my tank?
- Thread starter bozco
- Start date
Just add up how many watts of light you have and divide that by your tank capacity.
ie. If you have two 55 watt CF lights over your 55 gallon tank, then its 110watts/55gallons, which turns out to be 2watts/gallon.
Keep in mind, that the general rule of thumb for lighting a planted tank is made for normal flourescent lighting... when you get into CF lighting, metal halides, etc. the numbers get skewed a bit.
HTH
-Richer
ie. If you have two 55 watt CF lights over your 55 gallon tank, then its 110watts/55gallons, which turns out to be 2watts/gallon.
Keep in mind, that the general rule of thumb for lighting a planted tank is made for normal flourescent lighting... when you get into CF lighting, metal halides, etc. the numbers get skewed a bit.
HTH
-Richer
Another thing to think about is tank height. That is to say a 20g long tank should require less overall lighting than a 20g standard. The main reason behind this is that the light has less distance to travel in the water. Perhaps a better example would be a 40g standard tank is roughly 20" tall compared to a 40g long tank being about 15" tall.
Here's some advice that I would give to anyone starting out.
Start with between 1.5watts/gal. and 2.5 and learn how to balance your tank with 'low' lighting before moving up to higher light levels.
There is a huge selection of plants that you can grow in that range and you won't have as many concerns as is typically the case for those that start with 3 - 4watts/gal. You can always increase your wattage later, after learning the ropes.
Len
Start with between 1.5watts/gal. and 2.5 and learn how to balance your tank with 'low' lighting before moving up to higher light levels.
There is a huge selection of plants that you can grow in that range and you won't have as many concerns as is typically the case for those that start with 3 - 4watts/gal. You can always increase your wattage later, after learning the ropes.
Len
Good advise really. At 1.4 wpg on a 50g long tank I have a mixture of crypts and a java fern going good. I also have anacharis growing steadily, a compacta sword that looks real good, and some micro sword that I just added and still have my fingers crossed.
OK, so I have the two 13 watt compact flourescents on the 10 gal standard that makes it 2.6 watts/gal
two 13 watt compacts on one 5 gal that makes it 5.2 watts/gal right?
And one 13 watt on the other five gal which puts it at 2.6 watts/gal
Haven't looked at the bulbs on the 33 gal but it seems to be doing just fine without me knowing.
So the 5.2 watt/gal tank has no plants in it. Haven't got around to putting any in there yet, but when I do should I put in some that need more light? I mean the algae is growing great right now. Or should I remove one of the compacts and replace it with maybe one of those coloured incandescants so the compact is for the plants the incansecent is for the fish colours. I mean, if 5.2 too much light for the plants? Is that why there is so much algae dispite weekly 75% water changes? I probably feed the tank too much too. What plants would you suggest for it? It currently houses guppies and a single raspbora (poor guy was accidently scooped up in a discus bag)
Can you actually have too much light anyways?
two 13 watt compacts on one 5 gal that makes it 5.2 watts/gal right?
And one 13 watt on the other five gal which puts it at 2.6 watts/gal
Haven't looked at the bulbs on the 33 gal but it seems to be doing just fine without me knowing.
So the 5.2 watt/gal tank has no plants in it. Haven't got around to putting any in there yet, but when I do should I put in some that need more light? I mean the algae is growing great right now. Or should I remove one of the compacts and replace it with maybe one of those coloured incandescants so the compact is for the plants the incansecent is for the fish colours. I mean, if 5.2 too much light for the plants? Is that why there is so much algae dispite weekly 75% water changes? I probably feed the tank too much too. What plants would you suggest for it? It currently houses guppies and a single raspbora (poor guy was accidently scooped up in a discus bag)
Can you actually have too much light anyways?
Small tanks do not "fit" well into the standard rules of thumb for light loading. They generally use higher light than larger tanks.
If you can provide the balance of nutrients required lighting is fairly open ended. But that is a very big "IF". Unless you are already quite experienced with planted tanks and nutrient dosing, I'd follow Len's suggestion.
If you can provide the balance of nutrients required lighting is fairly open ended. But that is a very big "IF". Unless you are already quite experienced with planted tanks and nutrient dosing, I'd follow Len's suggestion.
This has been repeated so many times on this forum that if you use the 'search' engine you will find numerous threads regarding the light/fish/plant-mass suggestions.
You say you have 5.2 watts/gal. over a tank with no plants in it. A tank of that nature is guaranteed to have tons of algae. The amount of light should be in direct proportion to the plant mass etc.
In short, zero plants.....minumum of light needed. As you add plants, you can increase wattage.
"Can you actually have too much light.......?" It's a question of balance. Too much or too little of anything can/will cause problems. Add a ton of plants and find your balance.
Len
You say you have 5.2 watts/gal. over a tank with no plants in it. A tank of that nature is guaranteed to have tons of algae. The amount of light should be in direct proportion to the plant mass etc.
In short, zero plants.....minumum of light needed. As you add plants, you can increase wattage.
"Can you actually have too much light.......?" It's a question of balance. Too much or too little of anything can/will cause problems. Add a ton of plants and find your balance.
Len
Last edited: