Waaaaaaay too much light


Junior Poster
Jun 17, 2006
Durham, NC
I was reading another recent thread and wanted to pursue a topic that was discarded early on. Frolicsome_Flora wrote that "4.6wpg Waaaaaaay too much light" and then went on to describe the downside (the rest of FF's is below).

I am running a 180G with 640W (3.555wpg) of VHO lighting (10+ hours a day). I recently replaced the bulbs bulbs (all 3 years old... but they weren't dim at all... Icecap ballasts allow some long life in VHOs), lowered the lights closer to the tank (from 4" to 2"), and removed the glass panes that used to sit in-between (I built a new canopy that allowed the latter two moves). I was already at stagnant/slow growth with lots of brush algae :confused: before these changes and now I am experiencing a BGA bloom. :mad:

Depressed, I did a lot of Barr Report reading yesterday and decided to attack the problem by cranking up the CO2. The pH/KH ratio told me there was a lot of CO2, but I wasn't seeing any pearling and my internal reactor w/venturi loop wasn't misting. So I doubled the bubble count and improved the general circulation. After a few hours I got some very nice mist and lots of pearling (even some on the swords).

Based upon FF's post, I assume I would be better off with less light. If I yank one bulb, I get 480W for the 180G (2.7 wpg). Still too much? Any other suggestions for my setup? Anyone? :)

Thanks for any advice. I really appreciate the time you prolific contributers make here!! - Chris in Durham, NC (Raleigh Aquarium Society member)

Other info:
EI (50% wc per week)
1/2 tsp KH2PO4 3x / week
2 tsp KNO3 3x / week
3/4 tsp K2SO4 3x / week
27 ml Flourish daily
17 ml Excel daily
KH 6 (up from a natural 1.0 by adding baking soda)
GH 10 (after adding a lot of CaCl2 and Epsom Salts... very soft water in Durham, NC)
CO2 via internal reactor with venturi loop (using Tom's plan)
Heavily planted with as many different things as I can cram in there (42 species at last count) :eek:

4.6wpg Waaaaaaay too much light. Youll find that the plants were just taking advantage of the suddenly available high light. If youve not upped the CO2 AND nutrients to compensate for the massive light, then the plants wont be able to get enough, leading to deficient growth in whatever runs out first, probably CO2..

Turn the light down, let the plants get used to 2.4wpg with good solid CO2 and EI (this takes some time), theyll be pearling nicely after a few hours of lighting. A good solid stable slower growth, is far better than trying to run the tank at 400 miles per hour, running out of CO2, having massive algae problems, awful looking plants.. but lots of bubbles.

Also bear in mind, some plants dont pearl as much as others do anyway, Riccia is a very good indicator as to how you have things setup. If you see lots of nice little bubbles by 1/2 way through your photoperiod, leave it be.

A wise man once told me.. 'The only things that happen in an aquarium fast, are BAD'

Tom Barr

Staff member
Jan 23, 2005
Ask yourself what would more do to the CO2, NO3 uptake of your plants?

Would it increasing those demands, keep them the same or decrease them?
They would increase them.

So you need to add more CO2, namely I think the dosing is fine, but stressing the plants and letting them settle into the new lighting will help.

So do a 2x a week water changes and dose and keep the CO2 up till you can "right the tank" so to speak.

Also, if you see extra dirt, have done a lot moving around of the plants etc, do a larger than 50% water change.

That will reduce any algae issues afterwards.

The CO2 increase will help the BGA go away, it's likely not severe but appearing and can get out of hand.

I think a good cleaning, good CO2 and few extra water changes will clear things up for you.

Tom Barr