PAR at 0.8W/gal- or we really do not need much light

[Tom Barr]

I've converted a 60 Gal tank over to a different scape, got curious as to the light levels when I turned off 1/2 of the light. I'm still sitting at 28-35 micromols along the bottom sediment layer which is fine for most of the plant species. The tank is 24" deep, and the sediment is quire shallow+ the fixture is 14" above the tank to begin with, so about 1 meter away. Now.........if this is enough to grow plants, why do people still insist on telling others they need more than 3-4w/gal of T5 lighting? I mean even 2 w/gal of T5 lighting like this is a lot, even at 1 meter away!

Many will also not differentiate btw T12, reflectors, T8, MH's etc also, but still, those can be asked/mentioned. This same relationship held for the 120 Gal tank and 48" lengths. So why do we waste so much light and ourselves cause headaches not only for ourselves, but for the new folks? I've long advocated less light and then there is less worry about CO2/nutrients. So have others in the know. Many.......folks do not listen, do not test and then say more than they really know. This does not help anyone.

Hopefully more will come out against this myth that does far more harm than any nutrient management issue and is a root of the algae issues many seem to have.

Regards,
Tom Barr

 

[Gerryd]

Tom,

I think I have posted a thread or two on this myth since I have seen the light

I am using 1.3 wpg of T8 and providing slightly LESS PAR 20-30 at substrate than you have and so far so good.

Also 1 meter from substrate....

Stauro 049 and downoi are growing steadily but slowly.. I see no difference in the health of the plant from when I used >2.5 wpg of MH....The RATES of growth is all that has changed and is what I wanted...

I doubt I will ever use much more than T8 or T12 from now on with plants....

 

[Jim Miller]

Seems like for most folk two full length T5NO with good reflectors should work for "normal" height tanks. I'm planning to do just that for my planned 75g which is 48x21x18. Currently planning single clipons Miros by Icecap.

Should save electricity and still give manageable growth.

The light choices are definitely heavily weighted toward T5HO however. Not many places carry a variety of spectra in NO.

jim

 

[Gilles]

"I see no difference in the health of the plant"
interesting, you should see different growth patterns. According to Dutchy, his Ludwigia became much wider when using 50 mmol instead of >100mmol.
I am thinking of creating my new tank (1.76cm wide) with 6 rows of T5 39w, dimmable off course. With 849mm in length, i can create 3 rows of in total 6 tubes giving me optimal spread. Also, by using 6 tubes i can vary with color on one end of the tank.

However, i am not yet sure if i place them like this:
----- -----
----- -----
----- -----

or:
-----_____
-----_____
-----_____

if you know what i mean. Tank is 70cm deep (27.5")

 

[SuperColey1]

Can't agree more Tom. Still need to get the masses to believe. I still see a lot of Europeans especially those who are producing scape after scape using and suggesting very high lighting.

I myself found out (back in the flouro days. lol) that a single T5HO (0.9WPG) set 2ft above my 125ltrs substrate was still crazy fast growth.

Technology is a problem though. As new things come out they are marketed as the best and promoted heavily, then old technology becomes unfashionable and therefore less used and less choice.

T5HO is the best lighting.....for most users purposes. that being high bay warehouse or office lighting. getting more light into small areas etc. Not for planted tanks though. We should all have stuck with the 'nasty old fat tubes'.

AC

 

[barbarossa4122]

You folks are 100% right but, I do not think many ppl will give up on their t5ho lights. Wish I have a par meter and it looks like nobody is going to lend one even if I am willing to pay a deposit for the price of the meter.

 

[Gerryd]

Gilles,

I said the 'health' of the plant, not the SIZE of the plant. I never said that I did not experience different growth patterns...

I have smaller growth, but well formed, good color, no algae, etc. Growth is steady. I can see new Anubias leaves every other day with the minima. new bolbitus stalks, etc.

I don't necessarily equate large plants with healthy ones...and is all I wanted to point out...

The two can be mutually exclusive

Sorry for any confusion.

 

[dutchy]

The only downside there is (for me personally) is that the tank looks very dim at very low light levels, especially at a bright sunny day. I like it a bit brighter, which gives nicer colour to fish and plants. As some of you know my light is around 55 - 60 micromols, which doesn't give me algae problems.

I've encountered ony one plant that gave me trouble so far, Ludwigia Peruensis, which only wanted to grow with higher light. Also plant colouration is less, but it's an easy trade off. Better no algae than a little bit more colouration.

regards,
dutchy

 

[instantcrow]

Interesting. I was running a 12 watt 6500K Aquagrow 500 led fixture that put out 30 umol at substrate in a 60x30x30cm (11 gallon) tank with pressurized co2. I couldn't get HC to grow, it just withered and died. The hairgrass, wisteria grew quite well but not too fast.
Enter the DIY 12 Cree LED fixture I just built with dimmers. Been using it for two weeks. Now I have 80 umol at substrate. We'll see if the HC grows now. But I'm worried that I just bought myself an algae problem. Other plants are growing like mad.
My question: what PAR is necessary for good HC growth (assuming good CO2 and EI)?
Tnx
Instantcrow

 

[dutchy]

Well, you have to ask yourself if you can supply enough CO2 with that kind of light (and wear sunglasses lol) I've grown HC at 60 mmol with no problems.

regards,
dutchy

 

[Tom Barr]

Also, the difference btw say 20-30 micro mols vs say 50 is not that much morphologically.
I've grown HC at 40 without any issues. I've seen other tanks that do it, win competitions etc for HC/Gloss etc.


Regards,
Tom Barr

 

[bsmith782]

I think some plants require higher lighting and some dont but the majority can be grown in either. They may look different in the different setting but they will grow. For example, I used to have pressurized co2 and higher light on my mini m with s.tropica 49 and it grew much smaller and compact. Not I have it in the the same tank with out EI, Co2 or high light and it just grows taller. The same with Trithuria Sp but the only thing that changes was the lighting intensity. It grows pretty much the same in both cases.

It would be nice to have pics of the different plants in the different settings. Also to see which ones really do require Co2, high light and a strong dosing regimen.

 

[SuperColey1]

bsmith

You make an assumption there that is the light that made the change. You say yourself it used to be highlight, CO2 and ferts, now it is low light no CO2 and no ferts.

Have ruled out that it could well have been the CO2 addition or fert addition that caused the more compact growth? After all the CO2 may well be higher at the substrate level in a CO2 enriched tank and therefore in the non CO2 tank it may be reaching upward more to get more CO2!!!

AC

 

[Tom Barr]

Well, a light meter over time can illustrate quite a few interesting things.
Such as how low you can go and what changes occur as you do this, simply adjusting the light and guessing the PAR is not enough.

Not even close.

I have tried to guess then......I measured, I was way off.
I was thinking in the 10 range, maybe less.

I was off by 2-3x easy.
That was with the fixtures I've known and used many times.

If I'm that far off, and ADA w/gal ranges are also that far off etc........maybe testing light is a bit more informative than many seem to argue on other web sites.

Can you have a nice planted tank with a light meter? Sure........can you have a better one and manage it better if you use a light meter? Sure.
I can also use this same argument for CO2, I too can have a nice planted tank without CO2. So why should I bother?????

Same type of thing and logic.

Regards,
Tom Barr

 

[bsmith782]

bsmith

You make an assumption there that is the light that made the change. You say yourself it used to be highlight, CO2 and ferts, now it is low light no CO2 and no ferts.

Have ruled out that it could well have been the CO2 addition or fert addition that caused the more compact growth? After all the CO2 may well be higher at the substrate level in a CO2 enriched tank and therefore in the non CO2 tank it may be reaching upward more to get more CO2!!!

AC

I think its common knowledge that plants stretch to try to get more light.

 

[Gilles]

I think its common knowledge that plants stretch to try to get more light.

Not 'more' light, but 'other' light. Plants tend to grow compact with more 'blue' light.. AFAIK

 

[Hallen]

I think its common knowledge that plants stretch to try to get more light.

Not entirely true, as Coley already stated it's also the demand for Co2 what makes the distance between internoides increase. Low Co2 = more distance between noides. Plants try to grow upward and out of the water since the Co2 levels are higher there.

Also when plants have 'enough' light and more than enough nutrients and Co2 they will focus their energy in growth/colour etc. If they have more than enough light and nog enough nutrients they will focus their energy in finding nutrients and/or Co2. As you can see lighting sets the demand for nutrients, with 'low/medium' lightning it's more easy to get the small excess of nutrients hence the reason why plants can still look good with 'low/medium' lightning.

 

[bsmith782]

Not entirely true, as Coley already stated it's also the demand for Co2 what makes the distance between internoides increase. Low Co2 = more distance between noides. Plants try to grow upward and out of the water since the Co2 levels are higher there.

Also when plants have 'enough' light and more than enough nutrients and Co2 they will focus their energy in growth/colour etc. If they have more than enough light and nog enough nutrients they will focus their energy in finding nutrients and/or Co2. As you can see lighting sets the demand for nutrients, with 'low/medium' lightning it's more easy to get the small excess of nutrients hence the reason why plants can still look good with 'low/medium' lightning.

Ime, plante with less than optimal co2 grow in a stunted state with frail looking growth. As far as having excess/enough nutriens making them focus on color, anytime I have higher than normal N the red is always lacking.

How about we try to not pick apart our statements.

 

[Hallen]

When N is too low many plants will also color more red than with enough N. Dutch aquarists have been using this trick for a while to get extra red plants just before the tanks are being judged. Ofcourse excess nutrients cannot make a plant as red as high lighting would, the effects are more noticable in growth. i.e. more compact plants. I believe Dutchy has an excellent picture showing that effect.

 

[Tom Barr]

How/why plants actually stretch or elongation of the internodal distance is fairly well understood at the molecular level.

Severla good papers by Jackson et al, 2009 or so, have really put together the entire process.

Ethylene which is a gas phase plant hormone.........is the main signal that causes a cascade that promotes elongation.
How/why? For plants to avoid submersed conditions upon flooding.

This physical environmental change is what causes the elongation, or anything that mimics this.
Low O2, high Ethylene, anaerobic conditions..........like O2 and CO2..........Ethylene cannot escape rapidly from plants when the plant is submersed suddenly.
It's got that same 10,000 slower diffusion problem.

This elongation is independent of light.

However, one could argue and suggest that light is part of the equation for bolting to the surface, but.........much more research suggest it's more to avoid low O2, anaerobic conditions, ample CO2 supply.
Perhaps they will work more on the light + submersed conditions, but..........avoiding flooding is done pretty much independent of light intensities.

Stretching is general due to shading by other plants , but not things like rocks/wood/filters etc (also supported by molecular research- plants can tell if there's another plant they are competing for light with, perhaps algae can sense this well also), a good trim often addresses this issue. Good CO2 = > good O2 production by plant growth, good current = good O2 etc.

Good trimming etc, shaded leaves of Starougyne still do quite well, but under their own canopy? About 2-3" in, they start to get pretty yellowish, but there's hardly any light there.
Few things could grow under such a mat.

They do not bolt, rather, they use a different strategy.
Crypts/swords also can do something similar, and those old leaves? If they get algae etc, does not matter. Those leaves still block lots of light to anything near by.
Basically like attached leaf litter that buries competitors.

You can also argue stretching is reduced if you limit nutrients, but the size of the plants/growth rates also is reduced. But the absolute distance is reduced.
So why not limit the nutrients to reduce the distance?

Regards,
Tom Barr