I've said this several times in the past - but i'm just sharing my experiences - and guess that's why most of us post here.
I 100% tap water will be a NEVER ENDING problem. Not even if you dechlorinate and chemically treat it.
If you don't want the huge expense of a r/o unit - the long time it takes to make water (along with the huge amt of water waste it puts off) - I would recommend a D/I filter for tap water.
I use a product by AQUARIUM PHARMACEUTICALS - a tape water purifier (d/I unit). It cost about $50 to purchase and about $25 for replacement cartridges - that make about 75-100 gal of water each (depending on the lack of quality of ur water source).
Figure $25 for 75 gal is still only $.33 per gallon - cheaper than walmart - AND you don't have to carry the stuff back/forth. It does not take long - it's made at a trickles pace - about a gal every 5-10mins.
I have never had problems using this - and water tests on it have always been wonderful. Just another option for you to ponder.
The Filter removes:
DISSOLVED MINERAL including: Calcium, magnesium, sodium, potassium, sulfate, choride, carbonate, flouride
HEAVY METALS including: copper, zinc, lead, iron, cadmium, aluminum
UNDESIRABLE CONTAMINANTS including: phosphates, nitrate, ammonia, silicate, nitrite
CHLORINE AND CHLORAMINE
ORGANIC PULLUTANTS including: Insecticides, herbiides, PCB's and Pesticides
I have ONLY had an algae problem 1 time ever - and it was due to overfeeding. I was feeding my tank 2x a day or so. NOW, i feed maybe twice a week - and no algae problems. I find the fish are more productive also - eating off the back glass, the substrate, the rock, foraging for copepods, etc - isntead of just waiting for me to feed em.
Good luck - but I would defiately say #1 problem -get ride of pure tap water as a source. Many months from now - you will be telling someone else what a difference it made for you.