Re: High Light Tanks: How Much is Too Much?

[Jeff Ludwig <jeff at rockytop_net>]

> 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.

I actually have a 2x15 setup ready to go on a 10 gallon after this 
round of quarantine is over, so I'll give this a whirl and try to move 
some D. diandra clippings over.  I guess I have had some (better) luck 
over the last couple weeks (mainly due to being extremely busy) by not 
testing and only adding something to the tank by watching everything.  
I guess its the general inclination of trying to reduce everything down 
to a convenient number thats fallen out of favor with me... I'm 
*starting* to gain a feel for when the tank needs nitrogen, trace etc 
by looking at new growth.. For anyone either bored with an algae free 
tank or frustrated with testing I can recommend this as challenge/good 
learning process.

>> 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.

Well, this was part of my reason for coming out of lurking mode.  This 
is a plant that I have had trouble with under 3wpg and seemed to me to 
defy conventional wpg wisdom.  When I get the 10 gallon setup I'll try 
it under 2x15 and pay really good attention to ferts and see if I can 
get it to grow.

> 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.

Tom, it's nothing you actually add but more of a connection to the 
aquatic plant collective unconscious that does the trick.

> 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.

Well, maybe there is something here.  Why I would have luck with 
basically the same nutrients levels moving from 3+ wpg to 5+ wpg while 
you can grow just fine at lower light levels?  Is it possible that 
higher light levels are opening different metabolic pathways?  Or put 
another way, if my nutrient levels were less than ideal at 3wpg why 
would increased lighting fix the problem?  Or maybe that I was 
overdosing something whose uptake rate became fast enough under higher 
light to get it to a good, non-blocking level (maybe K+?)

> 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?

Absolutely not,  but I think a fruitful line of questioning would be 
what I mentioned above; what are you adding and I am not (or adding too 
much) that higher light levels are somehow compensating for?

> 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.

Right.  So with your new 800wpg tank we should have proper N-P-K levels 
down to 5 or 6 significant digits, right? :)

Cheers,
Jeff Ludwig