I would like to do better - crappy plant growth

You can do this

I remember posting about a year ago with long green stringy hairy algae. It was so long that where the goldfish swam through it, it was wound into dreadlocks! Oh man, I wish I had taken a picture!

Your water sounds a lot like mine, pH 8.2, GH 10 KH 8. Can you test the unsoftened tap to get complete water parameters? I did find that I had to add CO2 to my tanks to get my plants to grow, but I know people locally who do not and yet they still have nice planted tanks.

First, the presence of algae tells us that you can grow plants -- your lighting is probably about right. But, we need to know about the other nutrients in the tank.

Do you have any fertilizers? Any nitrate source? Potassium you can get from your softened tap water, it should be fine to use that, potassium is OK, high sodium is less desirable. You may want to get some unsoftened tap also, is that available at all? Phosphates are easy to find in several places, but you may already have some if you have pH reducing products. Or just get some from the pharmacy, but that is a bit later.

First, what is the light on this tank? What plants? What fish? What sort of chemicals have you been using in this tank? How big is the tank? Would you consider using CO2?

balance

You have 3 watts per gallon, so the plants are taking in a lot of nutrients to fuel the growth the light is pushing them into. Were yo having any algae during November when the root fertilizers were effective? If that was working for you, go back to using that!

First, cut back on the light hours you are providing to 8 or 10 hours a day. Actually, you ought to go to 40 watts of light if possible to get the algae under control.

General concenses from the plant professionals (university biologists, etc) is that all algaecides hurt plants. So don't use that.

As for test kits, I use pH and KH -- that helps me monitor the CO2 I add, then nitrate and phosphate -- for I add both of those also. If you exclusively use root fertilization, testing the water column wo't do you much good, though ammonia, nitrites and nitrates might result from leaking root fertilizers, maybe, so once in awhile you may need to test for that, but using commercial aquarium root ferts isn't something I'd worry about, using Jobes sticks or similar, I'd be sure to test for when that stuff leaks you get a heck of an algae problem (solved by topping the gravel to seal it in and doing massive water changes to remove leaked nutrients.

soil tank?

is this tank using soil? or gravel?

Soil makes it another thing entirely, out of my expereince so far.

OK, plain gravel, good to not deep clean it. You'd just stir up the fertilizers. Just sort of wave your hand over the gravel to fluff up any surface mulm and siphon that away.

Go back to adding the root fertilizers, if that doesn't correct some of the problem, you may want to add water column fertilizers.

Light drives the plants to grow. They will grow to the extent that they are able, being limited by nutrients, micro and macro fertilizers and carbon. In soil tanks the carbon is produced by the massive amounts of bacteria in the soil, in gravel tanks we get it from fish and mulm and carbon we add in the form of carbon dioxide, or Excel, or carbon from a carbo plus system or similar things.

When the plants stop growing due to exhausting somthing in the tank that they require for growth, then algae takes advantage of the nutrients that are left. (Over simplified and not exactly correct, but a reasonable start for understanding) Newly bought plants have a lot of stored fertilizers, but those get used up.

IMO, it is best to get started with lighting at about 2 watts per gallon. More than that and you really need CO2, at 2 or less, you may get by without it. But, even at less light, the plants will be much better with CO2. IME, it was the first thing I added to my tanks and it made a huge difference.

After light (and maybe CO2), then you want to test for nitrates, you'd like to have about 5 ppm or maybe 8 in the tank, never zero. Zero nitrates = algae in my tanks. The fancy goldfish hated nitrates, sulked when I added them, so I kept it really low and that tank was full of algae. Trace nutrients are important right fromthe start, try Tropica Master Grow or one of those types of fertilizers. Do this for maybe 3 weeks and keep records of how the tank looks. Trace fertilizers, 5 ppm nitrates, 2 wpg, and maybe CO2.

The Hagen CO2 system will work for that sized tank, look into it. It is really easy, no electricity, but the ladder is inside the tank, not that visible if you put it on one side or behind plants. $30 in the local store, less online even after shipping.