[hoppycalif]

Seachem Equilibrium will not lower the pH. It affects the GH, not the KH. You could try peat moss in the filter to lower the KH. I haven't tried it, but several people posting here have found it to be effective. Or, if you aren't trying the EI fertilizing method you could dilute the tap water with RO/DI or distilled water, sold at grocery stores for about a dollar a gallon. You would need about $50 worth to get the KH reduced by half, but you wouldn't have to do weekly water changes, so it would be a high one time cost, followed by small costs to maintain the lower KH.

 

[hoppycalif]

There is nothing wrong with your tap water. Just use it as is. When you add things like acid buffers you then always have to treat what ever water you use for make up water, or when you do water changes. It is a nuisance that doesn't gain you anything. If you had some of the few plants that really do prefer soft water it would be different, but you don't.