[Wet Thumb Forum]-Light limits?

[Roger Miller]

When I was keeping CO2-less tanks I found it impossible to grow a reasonable variety of plants in tanks with bright light. All but one or two species would waste away. The pH went very high (9+) under bright light, so I think that the best-adapted plants outcompeted the others.

I was curious what light levels people have been able to maintain in planted tanks without CO2 and still grow a variety of plants.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein

[Roger Miller]

When I was keeping CO2-less tanks I found it impossible to grow a reasonable variety of plants in tanks with bright light. All but one or two species would waste away. The pH went very high (9+) under bright light, so I think that the best-adapted plants outcompeted the others.

I was curious what light levels people have been able to maintain in planted tanks without CO2 and still grow a variety of plants.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein

[imported_RTR]

If your pH went 'way up, did one of the survivors happen to be Val or other plant capable of splitting out the carbon from carbonates/bicarbonates?

Some of us don't do wide (define "reasonable"?) varieties of plants so cannot easily answer your question - I get uneasy at max six species in a 55 - it starts getting "busy" to me.

I also don't do bright light without carbon supplement - about 2.6 W/gal is my top.

"Where's the fish?" - Neptune

[Roger Miller]

RTR,

Yep. Vals were one. Anubias nana, Crypt wendtii and Ceratophyllum demersum were others that made it.

"Reasonable" is probably whatever you find sufficient. I wasn't happy with being able to grow only three or four plant varieties in a tank. I thought that was unreasonable.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein

[Kevin Jones]

I've had non-CO2 tanks at about 3 - 3.3 WPG with ultra soft (less than 5ppm hardness) where the pH would shoot to about 7.8

crypts, echinodorus species, sagitaria, mayaca sp, ferns, mosses, water sprite, and lillies did well.

[Roger Miller]

JoneZay,

That's interesting. 7.8 is not that high as pH goes -- there would still be CO2 in the water. Where was the CO2 coming from?

I wonder if 3-3.3 watts/gallon is not enough light to drive plants into using bicarb.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein

[MarcinB]

I don't have much experience with low tech tanks, but I'd shoot for about 2 WPG.

150L (40G) planted tank
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[imported_Svennovitch]

I have never tried a low tech, bright light tank before. But I do have a tank with only 18 W over a 20 gallon tank. And Anubias, Crypts, Hygrophila polysperma and Vallisneria are growing relatively well. Not that fast and strong but growing...

Sven

[Kevin Jones]

I think the lower pH of my tanks was attributed to the peat being used in the substrate. that and to induce the apistos to spawn I would occaisionally use peat-soaked water in water changes.

Interestingly enough, I always had success getting the SA dwarfs in those tanks to spawn and rear their young.

[Roger Miller]

JoneZay,

It sounds like that tank had three sources of CO2 -- the respiration of the fish, the CO2 produced by the breakdown of the substrate and the action of the acidic peat on any bicarb in the water. Together they were enough to keep the plants from using up all the CO2 and pushing the pH over 8.4


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein