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Re: high light

> I wonder why this issue keeps resurfacing?

Well, this can be said for many things:-)

> We have all agreed that wpg is a
> terrible measure of light, yet we continue the debate.

I never agreed:-)
I still use it and it's worked in every case I done thus far.
Lighting type can influence this but adding PC's, MH's etc will only add
more light.

> I disagree with both
> of these statements.  4-5 wpg is overkill on a 100 gallon tank, but may be
> appropriate for a 10 gallon tank and all of this depends on the specific
> needs of the grower.

I don't think so. I've found it to be the same. 3 watts a gallon on a 10
gallon tank is more than enough to grow any set up(2x 15w).
Likewise, 3 watts a gallon on a 100 will also grow any plant etc.

Tank depth is important but plants can do pretty good with less lighting
than folks often mention.

George brought this issue up and most folks that have had tanks for more
than 10 years recall the days without PC lighting and the algae was less
intense, getting a number of parameters precise was less critical etc.
Plants looked good and did not grow so fast etc. No Green water issue really

> For those who don't think this rule can break down,
> trying growing Didiplis diandra with 2-3wpg in a small tank and a large
> tank.

Wrong, been there done that.
D. diandra is sensitive to mechanical injury and low CO2/PO4/NO3 levels etc.
Grows mighty well otherwise.

> I upgraded my lighting in a 15 gallon from 55W of PCF to 72W of PCF
> to keep Diandra stems from rotting, I would like to see pictures of good
> compact growth of this plant from a lower light, smaller tank if anyone has
> successfully done this... maybe I am missing something?

Gee maybe it's the magic Tom's miracle grow snake oil I add?:-)
Mine did fine at 2w/gal in a 20 gal and it did fine at 5w/gal in 75gal and
it a 90 gallon with 3.5w/gal.

I think water mixing is more important in larger tanks and folks tend not to
do the same large water changes that are easier on smaller tanks.
Smaller tanks are less work etc.
> Anyhow, my proposal is that we leave it like this:  use the least amount of
> light that yields the color, compactness and robust growth you want out of
> all of your plants.  If your glosso is growing vertical or stems are rotting
> near the substrate or colors are not what you want, add more light. How much
> light on your new tank?  Find the most light demanding plant in your setup,
> and ask around about what has worked for others in a similar sized setup.

But some twisted people like me did well at 1.5 to 2 watts a gallon on a ten
gallon tank while other will claim nothing less than 5 w/gal did it for them
on a 10 gal. 

Basic premise is that if someone else is growing plants with lots of PO4,
and they have no algae, does PO4 cause algae? If high light is required on
small tanks but someone else is growing nice plants with low light, is high
light required?

While it might be the solution for some folks, often it is not and results
in many sad algae stories.

A better area to consider and attack to make a tank look and grow better is
the nutrients and CO2.

I've run the gambit of light and substrate types. This just leaves CO2 which
is fairly easy to get correct after some work and then just nutrient levels
which are easy to manipulate.

It's not complicated unless you want to make it so. No witches brew, eye of
newt, fang of water spider or venom of cotton mouth needed.

Generally it's easier to maintain and there is much more wiggle room at
lower light values. 10-15ppm some of the day CO2 levels might be okay at
2w/gal of T-12's. But at 3w/gal of PC's this might need to be 20-30ppm.

But the 2/w/gal T-12 tank will still do even better if you maintain these
20-30ppm higher level. Same for the NO3, PO4 etc.

High light has made the narrowing of the ranges of good plant growth much
better IMO. Then this same knowledge can be applied to the lower light tanks
with great results.
Dosing is _less_ frequent at lower light but the levels _maintained_ are the
same. More light? More frequent dosing.

Tom Barr

> Any thoughts?
> Cheers,
> Jeff Ludwig