Help with Seachem equilibrium and buffers

[plankton]

Do the RO/tapwater mix and see what it is, as well as testing the RO, maybe a membrane has gone in the RO unit....??

[Valco]

Yes I have tested before adding anything.The pH is 5.5 both the Kh and the Gh are zero. Also the tds is zero.
Can I do a water change using RO water with just acid and alkaline buffers and no equilibrium would this safely lower the Gh.
I am beginning to wonder if the high Gh level could be due to a build up of minerals due to evaporation. I have heard of this happening but have no idea of how to correct it.
You opinion would be appreciated.

[plankton]

I've never played with RO, so don't know what this would do.
What acid/alkaline buffers would you use?

[Gingerlove05]

I’m wondering if adding both might be pushing the hardness up, or is there something in the tank decor wise thats raising the hardness?
Like Ian i have never used any buffers or equilibrium. I was trying to remember what Vale! uses, thats aquadur

[Valco]

I use seachem acid and alkaline buffers. The only rocks I have in the tank are lava rocks which are inert.
I have used JBL Aquadur remineraliser in the past and had the same high levels of Gh.
Perhaps I need to contact seachem direct to get their thoughts.

[plankton]

It is quite unusual to get such a high hardness level when using the remineralisers (when you're not aiming for it), I don't understand why that would happen......unless the batch has got too much of something in it....???