Always include the units.
GH and KH in this test are reported in ppm. This water is fairly hard, high levels of minerals.
The pH is weird. Usually with the KH so high it will buffer the pH at a higher level.
zero nitrates worries me for 2 reasons:
1) Nitrifying bacteria are not very active when the pH is so low, I wonder if they are not producing quite so much NO3. But the ammonia and nitrite are zero, and this is good.
2) Plants need nitrogen to live. When the NO3 test is zero it also suggests the plants are removing all the Nitrogen, especially the NO3, and may be deficient.
Seachem is a company that makes aquarium chemicals (and other things)
Flourish is their line of fertilizers for aquariums.
There are several products in the Flourish line.
There is Flourish Nitrogen, Flourish Phosphate, Flourish Potassium, Flourish Iron and a trace supplement.
There is a product called Excel. This is a liquid carbon source for plants. It also kills things. The secret is in the dosing.
There are several ways you can dose Excel to kill algae.
1) Use the regular dose on the bottle. It says to use a higher dose right after a water change, then the regular dose until the next water change. Some plants (and algae) are sensitive to Excel, and may die.
2) Read the label to find out the maximum dose your tank should have.
Put that much in a syringe (no needle) or eye dropper.
Turn off the water circulation (filter, power head, other)
Use the syringe to squirt some Excel deep into the thickest part of the algae. If there is an extensive invasion you might not get to treat it all at one time. Do not over dose the tank.
Turn the filters etc. back on.
3) Drain the tank or remove the object (rock, driftwood) and treat with straight Excel on non-living things, or slightly diluted Excel on plants. If it is something you can remove from the tank you can rinse off the Excel before returning the rock or wood to the tank. If you cannot remove the item then treat it right in the tank, but remember that much Excel stays in the tank. Again, do not over dose the tank.
Hydrogen Peroxide can be used in about the same way, but do some research about maximum dose. There is some controversy over what is safe.
If you need to treat again the next day, do a water change if you were going for maximum dose of either Excel or H2O2. These do break down in the aquarium, usually fairly quickly (like 24 hours) but it is better not to risk overdosing.