Is Too Much Light Bad For Plants?

[Joller]

My leafy plants are getting brown spots on their top leaves and the other plant is going a bit yellow, i turn the light on for around 15-16 hours a day

 

[Truck]

are they cryptocoryne species? what lighting have you got? its probably a nutrient deficiency

 

[Joller]

I'ts a 30W tube
I'm not sure about the plants, here's a pic

 

[kcharley]

The brown spots appear to be algae. The yellowing appears to be a nutrient deficiency. Sorry, I don't know what type of plant that is.

I'm a bit of a newb, especially on plants so if the more experienced members contradict what I write go with them.

To me, growing plants is a balancing of growth speed, light, carbon, macronutrients and micronutrients. Don't worry, it just sounds more complicated than it is. The faster plants grow, the more carbon and nutrients they need to sustain that growth. The more light plants get, the faster they try to grow. Algae likes a lot of light and low nutrients.

If it were me, I would back down the amount of light your plants are getting. Try limiting the light period to 10, maybe 12 hours a day, with a two hour break in the middle, if possible. At this point, you probably should do a water change, assuming you use tap water. Your tap water will probably have some nutrients.

This should get you time to study plant growing and the different levels of sophistication that are possible.

 

[OldMan47]

You should be limiting the light period to less than 12 hours. I keep mine between 8 and 10 hours depending on which tank and how the plants are responding. The plants definitely look like they are not getting enough nutrients. What are you using as fertilizer for the plants? If there are fish in the tank, they probably get enough nitrogen from the fish and phosphorus from the fish food but trace elements are often needed. Potassium can be supplied by frequent enough water changes if there is some in the tap water. I assume that as a beginner you are not ready to go out and buy special lights and lots of fertilizers so CO2 should also not really be needed. If you are going to get serious about plants, you need to go to the plant section where the serious plant people can help you a lot more than most of us here can.

 

[Joller]

Well its a special light that i got at LFS, but yeah I am a begginer and didnt know you need to fertalize the water.

 

[OldMan47]

Special bulbs are a money maker for the fish shop but are not really needed for plants. By special lighting I was talking about high wattage lights that would have meant an entire change in the ballast in your hood. The only need to fertilize would be if you got plant happy with high wattage bulbs and CO2 addition. In the typical low light situation that most of us end up with, 8 to 10 hours of light along with normal feeding of fish and water changes can give you a tank like this.

If you decide to go crazy with plants you can get very fast plant growth and very dense plantings. It takes special high intensity lighting and fertilizers to get to that point. I would advise that you get the fish aspect of the hobby under control and get really comfortable with fish before branching out too much.

 

[rdd1952]

It looks like brown algae. How long has the tank been set up? Brown algae is quite common in new tanks. It is diatoms that feed on the silca released by the silicone that seals the tank. The plant looks similar to anubis nana (probably not though). Most slow growing plants that can thrive with minimal lighting (flourescent lighting of less than 2 watts per gallon) are prone to algae.

I could just be a matter of nutrient deficiency though. Lack of the proper nutrients can cauld plants to turn yellow or brown. I agree that you should cut the lighting back. You really don't need more than about 12 hours a day. Plants (and fish ) need down time without lights. As for the break in the lighting, it really doesn't help with algae growth. Dave Spencer has posted about it numerous times if you want to search through his posts. I have a break in my lighting simply because I want them on when we are at home most to view the tanks.

As for the special light, Im not sure what it could be. Most of the lights they tell you bring out the colors in fish or enhance plant growth really don't do anything except cost more.

 

[aaronnorth]

yellow leaves = Nitrogen defficiency.

Plants get a source of N from ammonia, nitrite and then nitrate as a last preference. But obviously Nitrate is the only safe nutrient to add to our tank. Buy a fertiliser like tropica plant nutrition+ or Seachem Flourish, and dose weekly at the reccomended rate.

It is diatoms that feed on the silca released by the silicone that seals the tank.

I also agree that it is diatoms, however silica is not a cause of diatoms, i have posted it quite a few times over the past few weeks but in short, our substrates contain silica molecules which stay in the substrate for years

Diatoms is caused by the possible ammonia presence and low bacteria population, more so in the substrate.

 

[waterdrop]

I was thinking that that plant looked like an anubis nana (anubia?) too. I have one myself and I have plenty of that exact same brown/rust colored algae. But on closer examination the leaves of the pictured plant look more wrinkled than my anubia, which are extremely smooth. Maybe there are variations of that plant.

Anyway I too wish I could figure out the brown algae key things. I've noticed when I overdose Excel carbon I can get the algae to go from brown to more rust looking and almost looking like its standing up or loosening a bit and it becomes even easier to wipe off the leaves with my thumb, although the brown is always pretty easy for that it seems.

~~waterdrop~~

 

[rdd1952]

yellow leaves = Nitrogen defficiency.

Plants get a source of N from ammonia, nitrite and then nitrate as a last preference. But obviously Nitrate is the only safe nutrient to add to our tank. Buy a fertiliser like tropica plant nutrition+ or Seachem Flourish, and dose weekly at the reccomended rate.

It is diatoms that feed on the silca released by the silicone that seals the tank.

I also agree that it is diatoms, however silica is not a cause of diatoms, i have posted it quite a few times over the past few weeks but in short, our substrates contain silica molecules which stay in the substrate for years

Diatoms is caused by the possible ammonia presence and low bacteria population, more so in the substrate.

While I can somewhat understand the idea of ammonia and low bacteria being an issue as they are both prevelent in a new tank, everything I have read still points to excess silcates being the primary cause of diatoms. As you mentioned, our substrates also contain silicates and in new tanks, it would be at it's highest levels, meaning prime food for diatoms. That would also explain why you get brown algae in a new acrylic tank that doesn't have silcome seals to leech silicates into the water. In reverse, I haven't seen any article that mentions ammonia as a cause of diatoms.

 

[aaronnorth]

everything I have read still points to excess silcates being the primary cause of diatoms

I bet a 95% of sources also say that N&P still cause algae too

As you mentioned, our substrates also contain silicates and in new tanks, it would be at it's highest levels, meaning prime food for diatoms.

Exactly, it is food - not a cause. Something must bring the diatoms on in the first place (ammonia and/ or lack of bacteria) - diatoms will then feed on silica to build their cell walls (frustules). The same goes with hair algae. Lots of test were done on the follicles and it revealed that they were high in iron, so everyone assumed that excess iron was a cause of algae, it wasnt until they repeatedly added iron to a tank and it didnt induce algae, and they soon realised it wasnt a cause. This is the same for diatoms.