# Too much or too little light



## Water7 (May 19, 2013)

I have a question about a 10-gallon tank that I have. First I must say that I've experimented with different tank setups over the time I have been into planted tanks, and I have generally not been very successful, except with a 20 long I had on which I ran DIY CO2. This tank grew well and was very successful. Unfortunately, due to time and space constraints, I've eventually moved down to a 10-gallon, no CO2, with an air-driven sponge filter.

Some of my stem plants are not looking healthy. Especially ludwigia repens is losing lower leaves and dying back. Hygrophila corymbosa looks all right, and of course hornwort and anacharis grow. Crypts and anubias do fine as well. Hygro difformis loses lower leaves, and brazilian pennywort looks tatty. 

For light I have a standard hood with a single fluorescent strip light. It seems that the lighting is too low for some of these plants to thrive. However, I have quite a problem with hair algae. This algae moved from another tank which had developed it when sunlight was on the tank. It's interesting that I seem to have too little light for some of the plants, and too much light to be algae-free, but that is what it seems like. 

To be honest, this tank is quite neglected now as far as maintenance and fertilizing. This is unavoidable for me at this point, but it is likely part of my algae problem. Anyway, if anyone has any ideas, I'd be glad to hear them. Thank you!


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## Raymond S. (Dec 29, 2012)

Hygro difformis: Higher levels of Potassium needed.
ludwigia repens: Med light is minimum needed.
Check the type of algae. Hair algae usually needs lots of hrs or high light.
http://www.guitarfish.org/algae


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## Water7 (May 19, 2013)

Thank you, Raymond. That confirms my suspicion about the ludwigia. It isn't going to work in this tank. I have had some hornwort floating on the surface but I will continue with that to reduce the light. I'm also giving the tank a cleaning, so hopefully that will set the hair algae back.


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## Water7 (May 19, 2013)

Using the PAR chart I estimated my PAR in my 10 gallon tank to be around 45, since the T8 bulb is about 10 3/4 inches from the substrate. Does that sound realistic for a basic 10-gallon aquarium hood light? I had automatically assumed it would be low light, but it appears to be moderate light, and this would explain my significant problem with hair algae.

What should I do to make this tank work as a low-tech tank? Do I need to use Excel? I don't have any and would rather not. Add more fast growing plants? Add more floaters? Raise the light? (not the best option because it is a hood)

I think I do need to increase fertilization. I had greatly slacked off in this. (We have a baby now and the tank has not gotten near so much attention.) Could this be the reason my stems were losing leaves/turning yellow/dying back instead of lack of light or CO2? Hmmm, maybe so.

By the way, I've switched out the sponge filter for an AC30 and cleaned the tank, so things look much better, but the hair algae seems to be coming back, so I need to take further action.


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## Raymond S. (Dec 29, 2012)

I've heard it said by a few that the reflector in those plastic strip light fixtures (and the
hoods aren't any better)is not much. I think the kind on a shop light that curls around 
the top of the bulb is better.
I guess if you are using that chart from Hoppy it's fairly correct, just how good are we at
comparing the reflectors to see we are using the right line on the chart ?
I had two T8 bulbs in my 10g. Bad GSA on plant leaves but that was also poor choice
of plants involved because my Fissidens F. were doing well and there was Pearlweed that was doing fine. I'm a bit confused on that plant as someone put in a picture of it under higher, but not actually high light and it grows different than mine was.
So if I had two bulbs why was the growth pattern like those in lower light ?
But while the Pearlweed was there I had no problems till I tried an Anubias.
Forgot the Java Fern was also covered in GSA along/w the Anubias.
I feel that the 10g it's self is part of the problem as few plants are small enough to be in there without overtaking the tank so you can't see in there. That is the reason I took out the Pearlweed. Now I've had to remove one bulb. Still use it, but on a different timer with only 2 hrs. Trying to get some Water Sprite to grow so I can have a faster plant in there.
How many hrs are you running the light for ?


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## Water7 (May 19, 2013)

It has been a few days and I'm sorry it took me so long to respond, but thank you for your help. I have made some changes to my tank and things are starting to do better. I believe my main problem was lack of fertilization and perhaps lack of flow.

I've begun regular fertilizing again. Since the plants had taken such a hit, I also set up DIY CO2, and of course plants are pearling. So I hope they will be able to recover faster. I see now there were extremely obvious signs of nutrient deficiency, and I appreciate your bringing that to my attention!

Basically, I see a low-tech tank does not mean a no-effort tank--it wasn't working!


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