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How many watts is you light? My guess is either not enough light or not enough nutrients
Hi all,
My frog bits are turning yellow and like disintegrated. do they need totally calm water? I had a eheim liberty. there is wave motion on the top of the water.... is this the cause?
If for moving water, what floating plants are recommended.
Regards
Anthony
How many watts is you light? My guess is either not enough light or not enough nutrients
Since this is floating plant, I guess light is not much an issue since it is the closerest plant to the light without passing through the water column. Unless your light is really really low. I am not an expert so I may not be entirely rightOriginally Posted by pcfreak
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My guess is not enough nutrients.
Different plant have different photosynthesis starting point (refer to the graph). The graph shows that photosynthesis start when the light reach around 100 µmol quanta/m2/s. This light irradiance was measured beneath the leaf. Unfortunately I do not know how to convert this to lighting wattage
Based on experience, you can't grow frogbits and salvina natans under 9W, water lettuce need even higher light
May I know where to get this graph from ? I have a Light Meter with me and have done a small test on a 11W PL lamp at over 1 ft height (of air), it reads about 1200 lux. Under a hot sun in Singapore, it reads 84000 lux. I am still trying with difference combination of bulbs with and without reflector ...etc. I don't know what kind of losses when light penetrate thought free water column and hope to know from any brother/sistor here. If we can find out all if not most of the parameters needed for the formula, that will be interesting.
Just search for "photosynthesis light response curve", bunch of them on the net and all telling you the same thing. Note that quanta/m2/s was measured beneath the leaf. Light must be very bright until able to pass trough the leaf.
Since you have light meter that would be great, would you mind measure the light intensity on the substrate surface. You light meter may not be water proof, what you can do is put the light behind the tank and measure it from the front on the tank depending on the tank width you might get 1ft, 1.5ft or even 2ft. Unfortunately light meter may not measure the individual spectrum as you might already know it red spectrum dissipate very fast with depth.
Last edited by Shadow; 20th Feb 2009 at 13:19.
I found the way to convert Lux to Par: http://www.advancedaquarist.com/2008/2/review#h8
so 1200 lux/ 76 = 17.14 µmol quanta/m2/s ... that doesn't sound good, I assume you are using warm white fluorescent. PAR is depend on spectrum.
Is there a way to work backward? I mean how many watt PL light that gave you 56000 lux? This is the point where photosynthesis at saturation point.
Sorry pcfreak we kind of take over the thread
Last edited by Shadow; 20th Feb 2009 at 13:36.
Thanks for the link, very informative. From what I read, my light meter will not see the blue and red wavelength very well so the reading that I am gathering could be meaningless. Anyway I get about 32000 lux by putting my PL light directly on top of the light meter with seperation of about 10mm (i.e. 1cm) with reflector.I found the way to convert Lux to Par: http://www.advancedaquarist.com/2008/2/review#h8
so 1200 lux/ 76 = 17.14 µmol quanta/m2/s ... that doesn't sound good
Is there a way to work backward? I mean how many watt PL light that gave you 56000 lux? This is the point where photosynthesis at saturation point.
Sorry pcfreak we kind of take over the thread
hi all,
Update: new shoots are growing and the other leaves are dying.... i think it is due to the moving water... the earlier leaves not used to this.... moving water cause leaves to sink down under the water that is why it is decaying... But happy to see new leaves and shoots....
Regards
Anthony
i'm having the same problem, but mine's not frogbit but salvinias.
turn brown, get holes and rot away. don't think it's due to moving water.
and i thought maybe the light's too hot and made them melt away... haha. not sure. mine's 18W PL light and it gets pretty hot. even makes the water warm. my guess... lack of nutrients
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For your salvinia, its water movement. My light is at 55w and they are still growing. When i first got the salvinia, it too is turning brown and dying but after a month it grows new shoots and leaves.
I have had this problem with Frogbits and I believe it is temperature related. I've tested this several times, in my 2ft tank (25C, 24W PL) they grow like weeds and will cover the entire tank surface in about 2 months.
In my 3ft tank (29C, 25W PL + 20W Actinic) they start showing signs of what you're describing.
I put them into the 3ft they start dying, but once I transfer them back into the 2ft they bounce back.
Both tanks have comparable flow rates and circulation. The only difference aside from the temperature is the 2ft is at pH 6.8 and the 3ft at pH 7.8
The water of my taank PH is 7.5.
I got 2 corys and 4 neon tetra and 1 platy and 8 cherry shrimp.... If i lower the PH will it affect my pets?
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