Algae getting worse, do I need CO2?

[Ductapemaster]

I have a 20 gallon high with nearly 4WPG (I have some high light plants in there), and recently I've been seeing a rise in algae on my plants.

My nessea is covered in some sort of black algae (not the hair type) along with BBA. The new leaves look OK but as they get older they gain algae, presumably because they aren't growing as fast.

My Anubais has lots of GSA on nearly all the leaves, but I believe thats because I have high light. It's still growing well, so I'm not too worried about it.

I also get GDA on my glass about every week. I always clean it off when I do a water change, but it comes back every week.

Currently I am dosing Excel daily at the normal dose and Flourish every 4 days or so. I do a 30-40% water change every week. Water parameters are ammonia 0, nitrite 0, and nitrate 15-20ppm (can't tell the difference between the two colors on the chart). I run two filters, an aquaclear 30 w/purigen, and an aqueon 30 with just media, no carbon. Lighting is 4x18W T5HO's, 3x6500k plant bulbs, 1x10000k daylight, on 12 hrs a day. I also have a bubble wand in the back of my tank on all the time.

I just started a double dosing of Excel because of some of the algae articles I've read. We'll see if that helps. Other than that, because I have such a high light tank, should I just get a CO2 system? I've been on the fence about it for a while, and I'm definitely considering this as an opportunity to jump in. According to many algae articles I've seen my algae varieties all seem to have 'Low CO2' in their causes...

I can post pictures later if need be.

[HD Blazingwolf]

i'd go down to 1-2 of ur bulbs.. anthing over two is a LOT fo a 20 gallon with it being HO

that's the first thing i'd do before trying to go any further

or yes get co2. and be prepared to inject a lot of it, set a good fertilizer routine and maintenace routine for trimming, pruning, shaping and replanting because ur plants will grow fast
and old leaves will need to be trimmed. anything that has algae, is best removed.

successful high light tanks are backed by a well groomed maintenance routine

[Ductapemaster]

Thanks for the advice! I don't mind putting in more maintenance time. I actually really enjoy spending time making the tank look nice. There was a whole lot of work to do when getting the tank up and running (its been up for almost 2 months now), but now that its stable its kind of boring to maintain haha.

Also if injecting CO2 will make my plants grow faster I'm all for it. I'm somewhat impatient with my plants...they grow so sloooooow.

Welp, I'm off to amazon then

[HD Blazingwolf]

you will need a good fertilizer routine.. plants use more than just light co2, nitrates and phoshates