Diamond Fixture Questions (starting page 2)

[Rush3737]

Another quick question about this lighting.

I know that WPG is now obsolete, but 2-3 WPG was a rough guide for planted tanks as far as I could tell. Two of those bulbs would give me 64 watts to 55 gallons. What is it about the bulb/fixture that allows it to provide enough usable light to the plants?

[Rush3737]

Okay, and another question, one that kinda went unanswered earlier but I've partially solved.

I looked over some of Hoppys work again and reviewed this:



What this tells me is that if it sat directly on the glass in a 21" tall tank I'd have over 60 PAR, and without CO2 I read elsewhere here I'd be inviting Algae problems. So my question is what PAR is optimal to minimize algae while still getting good low-tech plant growth? This will allow my to figure out how high I want to raise the light.

OR, is simply running a light less than the usual 10-12 hours a day an option, or will that stunt the plants?

[sowNreap]

Actually the corrected chart is this one:


The chart you posted was before Hoppy realized the Lux to PAR conversion factor was off making it appear the light did much better than it really does. It still does a good job for a cheap fixture.

The updated chart now makes it appear that the diamond plate fixture is not that much better than a regular white painted surface shop light which you might be able to get cheaper. Although I really like the look of the diamond plate over those shop lights. On this chart double the PAR for the white painted fixture because as charted it's only for 1 bulb lit not 2 as in the diamond plate fixture (makes the diamond plate fixture look much better until you realize you're comparing 2 bulbs vs single bulb). I still think the diamond plate should do much better than the white painted fixture because the reflector is so much better. But for some reason it doesn't appear that way on the chart.

As to how much light before needing pressurized CO2, I'll quote what Hoppy wrote:
I don't believe there is any consensus about the definition of low, medium and high light. But, here is my definiition, subject to, and almost certain to change:
Low light - 15-30 micromols of PAR - CO2 is not needed, but is helpful to the plants
Medium light - 35-50 micromols of PAR - CO2 may be needed to avoid too many nuisance algae problems
High light - more than 50 micromols of PAR - pressurized CO2 is essential to avoid major algae problems

I've got a weird setup or I'd provide more info on my results using the diamond plate fixture.

[Rush3737]

Okay, so then I'll be at 50 Par, which could still very well lead to an algae problem according to what I read, which is exactly the quote you posted. This means I should at least go about 5 inches above the tank with the light I think.

[Hoppy]

My tank is a low light tank now. I have used about 20 micromols of PAR for most of the past year, and algae is a very minor problem. For awhile I had it at 25-30 micromols of PAR, and was seeing a little more algae than I wanted to, near the top of the tank, which caused me to drop the intensity to about 20 micromols. This is with a LED light, and measured PAR with the Quantum meter, adjusting the LED driver current to lower the PAR. I think 25 is a better number for plant growth, but, with DIY CO2 the plants do well with 20. A lot depends on how much algae you are willing to accept - meaning how much maintenance is too much from your perspective.

[funkman262]

Originally Posted by Hoppy

My tank is a low light tank now. I have used about 20 micromols of PAR for most of the past year, and algae is a very minor problem. For awhile I had it at 25-30 micromols of PAR, and was seeing a little more algae than I wanted to, near the top of the tank, which caused me to drop the intensity to about 20 micromols. This is with a LED light, and measured PAR with the Quantum meter, adjusting the LED driver current to lower the PAR. I think 25 is a better number for plant growth, but, with DIY CO2 the plants do well with 20. A lot depends on how much algae you are willing to accept - meaning how much maintenance is too much from your perspective.

But with the proper LEDs (proper as in correct spectrum, ideally peaking around 450nm and 680nm), 20 micromols of PAR will be much more effective than let's say 20 micromols of PAR from a full-spectrum bulb which from the spectral graphs I've seen tend to have huge spikes in the green-yellow range (which isn't completely wasted PAR, but it's definitely not as efficient for photosynthesis). So with an efficient LED fixture, 20 micromols PAR can easily put you in the high-light range.

[Rush3737]

Originally Posted by funkman262

But with the proper LEDs (proper as in correct spectrum, ideally peaking around 450nm and 680nm), 20 micromols of PAR will be much more effective than let's say 20 micromols of PAR from a full-spectrum bulb which from the spectral graphs I've seen tend to have huge spikes in the green-yellow range (which isn't completely wasted PAR, but it's definitely not as efficient for photosynthesis). So with an efficient LED fixture, 20 micromols PAR can easily put you in the high-light range.

So then to see the best plant results I'd probably want to be around 40 or so with the Fluorescents it seems. I think I'll figure out a way to suspend the light a bit to achieve this and then battle any algae problems if they arise. Luckily the tank will have time to develop before any fish are added so I'll have time to get whatever algae help is needed and go from there at first.

[Hoppy]

Originally Posted by funkman262

So with an efficient LED fixture, 20 micromols PAR can easily put you in the high-light range.

I don't think that is likely to be true. Have you seen any data to show that it is?