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I have a 15 watt 18" blacklight mounted to my 29g tank because of my Glo-Fish. The only other light in there is an 18 watt flouro bulb...

My plants are growing like crazy in really low light... Elodia growing an inch a week, hornwort growing 2 inches a week, my aponos are taking over the tank, dwarf lillies growing an inch a week, and my pothos vines are growing about 6 inches a week!

My 18 watt bulb is on for 12 hours a day, and my black light on about 12 hours a week. I don't use CO2, and I rarely dose ferts. I'm not sure what my nitrAte levels are (I lost the color card, but I'll test them and make a guess), ammonia is at 0 ppm, and my pH is probably around 7.1- 7.2...I'll check them all in the morning.

My stock list is as follows (I know it's overstocked...I just have it overstocked so my plants have more nitrAtes...)

Fish:
3 Danios
6 Peppered Cories
5 Blackfin Cories (I will be getting 1 more)
5 Ottos (I will be getting more)
1 Sward-tail
2 Ghost Shrimp
2 Hillstream Loaches
2 Neon Tetras (I will be getting more)
1 Dojo Loach

Plants:
15-20 Anacharis
2 Aponos
3 Dwarf Lillies
3 Pothos Vines
5 Hornwort

22" 18 watt flouro bulb
Will be replacing with 4 25 watt CF bulbs

Whisper 20-40
Penguin 125 w/biowheel


Any ideas about why my plants are growing so fast? Will the blacklight help or hinder the plants, and how? Any other suggestions?

Well all of those are really fast growing plants, they do great in medium light conditions, so i don't think is the blacklight.

Reading your stock list, i think that it's your tank that is thriving with nutrients and nitrates which all of them love to suck up.

Still, they're growing about 3 X as fast as normal...and it's in about 0.6 wpg of light, most of it blocked by my floating hornwort and apono leaves. Elodea shouldn't grow that fast in these conditions, nor should any of these plants.... I don't know why they are growing so fast for the past month...I'm not doing anything different, and suddenly they start growing 3X as fast...it's not just one plant, it's all of them...

It's perplexing....

IME Aponogetons have like this "going crazy" period, where they grow fast and they grow big! they develop a lot of leaves, then they calm down and just keep all those leaves. Lotus bulbs, I'm always saying that if you stay long enough in front of the tank you can even watch them grow it's like a bulb thing, then they will become dormant and all the leaves will fall.

I don't have much experience with hornwort, but from what I've read in other threads here it think it's normal. Elodea is one of my favorites because of that it can really take over a tank, even in low light conditions, the only difference is that the space between each leave growth becomes larger, but remember it's considered a pest.

And finally almost all the plants you have do compete for light, it's in their nature to send really long leaves to the surface, elodea gets huge till it reaches the top, same with apons and lotus so I guess they are all making and effort to get up there and fight the horwort.

Whatever it may be causing it, you are a lucky guy!

The scary thing is I took my 15 watt bulb off of the tank a few weeks ago...i used to have it mounted to the front of the tank and it bumped the light up to 1.1 WPG...

Elodia growing an inch a week, hornwort growing 2 inches a week, my aponos are taking over the tank, dwarf lillies growing an inch a week, and my pothos vines are growing about 6 inches a week!

Not to burst your bubble, but that isn't that fast for growth. As posted, they are all fast growing plants to begin with. With more light they would grow so fast that they would overrun the tank in a week.

The blacklight probably doesn't have any effect on the plants' growth. The growth you are seeing is probably due to the fact that the tank is overstocked and the fish waste is fertilizing the plants. In turn the plants are doing you a favor by keeping the water quality up.

I know...but they're growing a lot faster than normal...in that amount of light they're growing really fast...

Elodea is a low-high light plant...it will grow in lowlight, but it does best in higher light... how fast does it grow in 6 WPG? It was growing 2 inches a week in my tank w/ 6 WPG... but it grows an inch a week now in 0.6 WPG? It was growing at a more proportinate rate before...but everything suddenly started growing really fast...