Increasing Co2 and Ferts with Bioload, but what about light?

[mindfestival]

Afternoon!

As the title suggests, as I plant my tank up more densely, (95 gal with carpet, mid and background plants), obviously I will be upping my co2 and ferts, but what about my light?

Does light follow the same measure?

My tank is happily cruising at 0.7wpg of t5HO, with great co2.

I can increase this to 1.5 or 3.5 at the flick of a switch, but am enjoying the low light comfort at the moment.

[Noahma]

Originally Posted by mindfestival

Afternoon!

As the title suggests, as I plant my tank up more densely, (95 gal with carpet, mid and background plants), obviously I will be upping my co2 and ferts, but what about my light?

Does light follow the same measure?

My tank is happily cruising at 0.7wpg of t5HO, with great co2.

I can increase this to 1.5 or 3.5 at the flick of a switch, but am enjoying the low light comfort at the moment.

the WPG is WAYYYY outdated and useless with anything other than T12 lights. Light drives the tank, so lower light, less requirements for co2 and ferts. If you increase the light, you will increase demand. If you are happy with the way the tank is growing, and you are not having any problems then I would keep the light levels the way they are. If you start wanting to grow more light demanding plants, then increase the lighting, but be prepared to change the fertilizers and co2 more if the tank looks like it needs it.

[jcgd]

Well, as long as you use the "WPG rule" in the proper sense, which the OP is, there is really nothing wrong with it. If the OP is using the same light and running more bulbs, the watts per gallon is more a measure than anything, referencing off their own unique setup. Nothing wrong with this use of WPG at all.

If a person has say, 40 umol of par at the substrate running two bulbs in a four bulb fixture, you can assume that if you turn on all four bulbs you would have about 80 par.

OP, if you tank is absolutely packed you may need to increase the light to effectively have the light levels stay the same. This could have implications of raising the light levels at the surface to a point too high, and even if you only do one jump, you would be doubling that par. If you were to increase the light, keep in mind that the whole balance is going to change and you'll want to be prepared to rework the co2 system and fertilizing.

Personally, I would want to use a par meter and jump up my fixture output quite a bit. I would then raise the fixture in order to have more uniform light levels and hopefully decrease the amount of par at the surface while getting the light I need at the bottom. However, this can only be so practical as you may not be able to raise the light high enough to reach the goal, or not want to have all the spill. From a par point of view though, that would be idea.

[mindfestival]

thanks guys.

Yeah I know all the rookies and the use of the WPG rule.

I find it is the best measure for me, given that I have 8 bulbs and of which I am only running 2.

Interesting that I would have to raise the light slightly, for the light levels to effective stay more or less the same.

Given that my adequate co2 is enabling maximum light utilization, ( this thread is not about how I am measuring and monitoring co2, so lets not go there, its is cranked right up, lets just put it that way) I am surprised that light is seen as a commodity also. Does make sense.

So in theory, light CAN become a limiting factor simply by increasing the bioload. ( I know it would be an extreme example)

Maybe its opening up a can of worms.

So, in answer to my question, the answer is.... yes haha.

[jcgd]

Originally Posted by mindfestival

Interesting that I would have to raise the light slightly, for the light levels to effective stay more or less the same.

So in theory, light CAN become a limiting factor simply by increasing the bioload. ( I know it would be an extreme example)

Maybe its opening up a can of worms.

So, in answer to my question, the answer is.... yes haha.

Well, the height you have to raise the light may be "slight" but could be quite a bit... I'm too lazy to actually do the math. But you could keep more even light levels throughout the tank by running extra bulbs and really raising the light up. I think you already understand, but for others, it's like the sun. If you go outside and measure the par at 15 feet off the ground, it'll be the same as at 2 feet off the ground because we are so far from the sun. We can get the same effect (not nearly as uniform though) by raising our lights. The further away from the bulb you get, the less the light drops off.

As for light being the limiting factor, that's what you always want. Way easier to balance than limiting ferts, or especially co2. Most beginners (even those with tanks for many years) will limit co2. Most tanks that are "failing" will perk right up with the addition of co2. Co2 is like the miracle drug. Deficiencies can hide longer but ferts are an easier base to cover with EI.

[mindfestival]

Appreciated.

[Hoppy]

Consider a tank with just low growing plants in it. If you have the substrate 20% covered with those plants, then let them grow to cover 100% of the substrate, you don't need any more light. Unlike fertilizers, the light is not consumed by the plants, making it unavailable to the other plants. It just shines on the substrate. Where heavier plant mass does affect the light is by shading lower growing plants. But, that shade is still blocking light even if you double the wattage of the light, so that does little or no good.

So, my answer to your question is no, you don't need to increase the light intensity as the plant mass builds up. Instead you need to increase your pruning.