uh oh not again, dam algea picks included!!

at 3 watts per gallon it is better to have a heavily planted tank. Plants from aquaticplantdepot and aquabid are cheap and of good quality. Use less liquid fertilizer until u add more plants. Flourish excel will help with the carbon. DIY co2 is so easy but its not necesary. I had 3wpg for months with no co2 and no algae. To do co2 all u need is a soda bottle, attach a tube through a hole in the cap, use silicon to secure it and then use of of the many yeast sugar water solutions. Stck the output end of the tube into the intake of your filter or place a small glass bowl or the bottom of a soda bottle in teh aquarium and put the output of the tubing there. You dont need counters or scales or anything. My algae eating team is amazing. I have nerite snails (green spot algae), amano shrimp (hair algae), otos (brown algae), and TRUE siamese algae eaters (red algae). Bunhc plants are heavy consumers of nutrients in the water column so lots of bunch plants will help. I recommend rotala indica, elodea (anacharis), hornwort.

At 3wpg carbon supplementation is necessary in the general case. That's not to say that some folks can't grow plants without algae successfully with 3wpg, but you're definitely into lighting that needs extra carbon.

Definitely cut back on your fert regime. Do you have a test kit for NO3 or PO4? It's not necessary, but if you can get them tested it would be helpful. Keep in mind, of course, that these kits are only accurate to about one colour range, so don't stress the exact number.

Carbon (either as CO2 or Excel) is the key to fighting algae. Adding fast frowing stems can help if the growth conditions are there for them, if not, it's just more food for the algae as they break down. Get some form of bio-accessible carbon in there.

Next, remove all the dead/dieing leaves, they're not helping. How often are you feeding your fish? It looks like you've got some green water. Speaking anecdotally (gulp!) I get hair algae when I'm overfeeding.

Finally, do a 50% water change, maybe 2 back to back.

The goal is to reset your system and provide proper and ideal growing conditions. Algae eaters will help with small algal growths, but not with full scale blooms.

aside: depending on where you live you may not be able to get Elodea, it's an invasive species. Ask instead for its relative Egeria densa.

Get ready because the eyes are about to start rolling......all over the forum !!!
I have a pet peeve about 'nutrient tabs'. IMO, they are unnecessary and in many cases counter-productive, especially in newly set up tanks where plants are moved about fairly regularly. The reason is that it takes 2 - 3 months for them to 'spend' themselves and in the mean time if they are disturbed and their contents allowed into the water table they can/will create algae issues exactly like those that you display in your pictures.
Now this may not be the entire problem with your tank, but I'd bet it's a contributing factor, at least. Also, 3wpg requires heavy planting and fast growth.
Happy's suggestions regarding multiple water changes and the addition of SeaChems Excel, for your size tank would probably do wonders for it. Excel will force growth in the plants currently in the tank.
Then I would suggest not moving any plants until the tabs you've already placed have spent themselves. And, if possible start fertilizing with 'water table' nutrients, which IMO will be safer and more effective than the tabs.

Len

Start off buying a good nitrate test kit and a good phosphate test kit, or go to Tom Barr's site http://www.barrreport.com/ and read up on his Estimative Index and follow it.

You cannot balance nutrients and lights and carbon availability if you have no measures of those other than the lights unless you follow a proven path.

BTW, Flourish tabs are traces only, no macros, and you definitely need both macros and available carbon.

What are the liquid nutrients you use? It is hard to make suggestions without info on waht you are using.

I disagree about the plant tabs. If you do some research you will find that many plants take up certain nutrients much easier through their roots in the substrate and some can only take them up through their roots. They also last longer int he substrate rather than int he water column. Co2 is NOT necesary. There is a lot of debate about it right now and a lot written. Some people describe it as a fad or a love affair with co2. co2 will artificially create accelerated photosynthesis. I JUST started adding co2 to my aquarium. I did it before and saw no change with my DIY co2. Now that I have some more difficult plants I'm using it along with excel. I have 3 watts per gallon, no co2 for a year and my aquarium is algae free, has always been algae free. I have a correct balance of nutrients and lots of plants. My plants grew fine. Plants that grew great with NO co2: swords, java fern, java moss, anubias, crypts, rotala indica, dwarf lily, chain sword, vals, anacharis, hornwort, penyywort, ludwigea reopens, water sprite. Co2 helps to increase plant growth, impede algae and allows u to grow some of the more delicate red plants. If you have trouble with algae u need to find a balance with your ferts, try cutting down on the nitrogen and phosphates first. Don't add phosphorus or nitrogen and do water changes. More plants the better to outcompete the algae.

KOTG - I think that you may find that your experience is not the usual one. I have to supplement carbon in a few tanks just at or over 2W/gal (which is also not common) or I get hair algae. I always supplement carbon at and and above 2.5W/gal. That is the most common experience from what I see on the boards.

The Hagen/Nutrafin Natural CO2 system isn't terrible, and it'll work with a small tank. However, the best part about it is the diffuser/bubble ladder. For the main component, as you put it, it's just a pretty pop bottle.