Light Advice, Please

T

tackful

AC Members
Mar 15, 2007
649
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18
Sausalito, CA
I recently installed a 55 watt "Bright Kit" over my 29 gal tank. I'm slowly increasing the hours from 6 to 8 so far. Is this enough? Despite fert sticks and liquid ferts, the plants aren't doing too well.
I started with a 5500 K bulb, but it made everything yellow (possibly due to tannins from large driftwood?). 6700 K is better, but the driftwood looks green. Would 7800 K produce a more natural appearance?
A LFS owner suggested 1000 K. I've read that 7800 K is the upper limit for freshwater plant growth. Is this true?
Thanks for the help. Tackful
 
The K value shouldn't matter all that much and is much more about personal preference. I would be more concerned with the amount of wattage you have over the tank. 2-3 watts per gallon is usually a good amount. You didn't mention what type of plants you have and how long they have been in the tank. Also, how long have you had your new lights? I wouldn't worry too much about increasing the amount of time your lights are on slowly, it doesn't really matter.
 
I have wysteris, java fern, and annubias in 29 gal tank, which is 3 months old. Plants were there from the start, although I only upgraded the light a few weeks ago. BTW, have been using Flourish Excel (carbon), and just recently a potassium supplement. I wonder if the potassium could have caused a recent rise (0.4) in pH. Thanks for the help. Tackful
 
Java Fern and Anubias are fairly slow growing plants in my experience so I would just give them time. I don't know much about Wysteria though. How often do you do water changes? If you don't do them often enough the plants can use up all the nutrients that are in your water column. Also, you might want to consider dosing other ferts besides just carbon and potassium because it doesn't seem like you are getting enough from just the water. I would look into the Estimative Index method or if you want something low key just go with some more of the ferts in a bottle.
 
8-10 hrs of lighting should be enough, can try increasing the light to 10 if you're suppling the nutrients and still not getting good growth.

K rating on the bulbs isn't important, I use 10,000k bulbs with success.

Wisteria is a fast grower that does ok in low light but can grow very fast with more light and is a nutrient hog.

Potassium won't raise your pH.

Nutrients that you need to account for besides carbon and potassium:

nitrates
phosphates
trace minerals (micros)

In a low light tank, enough nitrates and phosphates may be provided by the fish and fish food. You will need to account for the micros, Seachem Flourish for example. Water changes can also provide some micros as most water sources contains small amounts, you will need to do more than 15% though.

If you choose to follow the EI method don't follow the dose amount too closely for a low light tank, it's designed for high light tanks. Reduce the amount of ferts by half.
 
k rating is the heat or color the bulb puts out... most use 6500k because the bulb puts out more red and blue wavelengths, which are the colors plats use the most.

if you want significant growth then i suggest minimum of 8 hours

and have you found out haw many watts your running?... most plants do well with 2-3 watts (as stated above) and low light plants can fare well under less than that and the high light plants require more than 2-3 watts.
 
Am now running 9 hrs at 55 watts. Began doing 1/3 water changes this morning, along with starting an Iron and Trace mineral supplement. Appreciate the advice about starting conservatively with the EI method;it makes sense. Point of interest: the manufacturer of my Potassium supplement (Brighty K by ADA of Nature Aquarium fame) states in the product literature that it temp raises pH. Thanks for the help. Tackful
 
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