Marine Leds In Fresh Planted Tank?

[simonas]

I converted my Aquareef 300 into a freshwater tank last year from a reef. It is a tank designed for marine really. I have TMC iLuminaire 900 LEDs which were great on my marines but not sure how suitable for freshwater and plants.
 
I bought giant vallis, vallis, swords when I set the tank up in September but the vallis and swords have pretty much gone. They went all brown see through and disappeared bar the small leaves that are now left.
 
Are my lights too bright? Too much white, blue or colour?
 
Help?

 

[Byron]

We will need more data in order to accurately diagnose the issue, but I would definitely say the lighting is a major factor.  Marine tank lighting is high in the blue with very little red and green, as this is what corals and such require.  Freshwater plants need blue and red to drive photosynthesis, and adding green to the mix further helps.  This deals with the spectrum or light colour, but there is also the intensity.
 
Byron.

 

[Chad]

I've used marine lights for plants before. The blue was never an issue but the brightness can be depending on the plant. My lights are controllable so I can dim them but if you can't you might have to make decisions on plants, plant placement, shading etc. 

 

[simonas]

cheers, yes I can dim them and alter the intensity or white, blue and colour I just have no idea of what kind of light and colour intensity I should go for

 

[Chad]

That's going to depend on the plants of course. If you had a PAR meter you could test. But experimentation should work as well. The manufacturer might have some PAR readings for you at various settings. 

 

[StevenF]

My guess is that your lights initially allowed rapid plant growth that depleted the water of nutrients.  Without nutrients the plants would slowly start to die.  The next time you performed maintenance you cycled water.  That restored some of the nutrients but not enough to fully restore the plants.  You may need a good micro plant fertilizer and maybe some macro fertilizers.  Dimming the lights would help by slow growth and reduced nutrient consumption and help stabilize things.   I use SeaChem Flourish comprehesive and Seachem flourish nitrogen in my aquarium with good results.  
 
In nature the sun puts out about 24,000 lumens of light on a clear day at noon with significant infrared and UV light.   Yet you willl find healthy plants in lakes and ponds.  Most fresh water aquariums only have a tiny fraction of outdoor lighting levels.  The main difference is a lake will have vastly more water and as a consequence vastly more nutrients.  With streams constantly delivering more nutrients The plants probably cannot keep up with nutrients delivered to the lake.  In contrasts Aquariums have vastly less water and significantly limited nutrients.  If the plants cannot get enough nutrients they will eventually die.  If you triy to grow aquatic plants in RO water they will all eventually die.  RO water has no micro and macro  nutrients and plants cannot grow in without them.  
 
Most plants do very well with red and blue light because photosynthesis works best with these colors of light.  Plants will also use use violet,green, yellow and red light but less effectively than blue and red.  So I don't think the color of the light in your case is the cause of your problem.  However marine lamps generally put out a lot more light than a typical fresshwater aquarium  lamps so I think that is your primary problem.

 

[simonas]

 so dim the lights more reducing the plants need for nutrients and add niutrients?

 

[Byron]

I am still of the view that the primary issue here was the light.  You have not provided any data, so everyone (including me) is guessing.

 

[simonas]

I am still of the view that the primary issue here was the light.  You have not provided any data, so everyone (including me) is guessing.

 
What data regarding the lights do you need?

 

[Byron]

 

I am still of the view that the primary issue here was the light.  You have not provided any data, so everyone (including me) is guessing.

 
What data regarding the lights do you need?
 

 
tcamos mentioned the PAR.  I think we need to have some idea of just what sort of light this is.  Intensity is one aspect, and then there is the spectrum (colour).  I may not have much to offer from this data, but I'm sure others will.  My only foray into LED was a disaster, and I am still using T8 which I know inside out and have used successfully for more than 20 years over planted tanks, so I don't say much about LED.  But every unit can be very different from both aspects (intensity and spectrum) and this is the single most important aspect of aquatic plants.
 
It is impossible to suggest fertilizers without having some idea of the intensity and spectrum because these (light and nutrients) form a balance.  The aim is to have a balance suited to the plant species, without encouraging algae.
 
Byron.