Grout discolouration

[JustDave]

Hi all, I'm new here, a hobbyist DIY'er, and try to learn the correct and smart ways to tackle home DIY.
Need some help please. I had tiled my bathroom a year ago, it was my first time doing so.
Over that year, where the water hits the tiles, the group has started to grey and discolour, like it's staining.
Some areas where water hits it's ok, but others are bad. I've scraped out the grout once in the bad areas and it's still disclours.
Both times I used the same grout brand/type.
I've attached some images to give an idea on what I mean.
The grout I used was Palace Tile-Grout, in white.

Any ideas what's going on? Theres nothing in the bathgroom used that stains, I've been through the lot.
I'm stumped and peeved on how ugly it gets. I've not used a grout whitener or anything as I don't want to mask the problem.
I've read about sealing, but as the grout iteslf is water based, suitable for bathhrooms, and in wet areas with no indication that sealing is required, I haven't done so.

Thanks in advance

 

[JustDave]

Anybody any ideas, please.

 

[Dave]

Hi. Do you rinse the walls after showering?

 

[JustDave]

Hi, thanks for chiming in. Yes, absolutely we do. Even if it was occasionally missed, it never occured on the old tild/grout.
Could grout be a cause, reacting with something?

Thanks

 

[eddcottee]

I dont know what's causing it, but you can get "Mapei Fuga Fresca" in various colours which is a grout reviver, but also you could chose a different colour to what you have at present and change that grout colour to a grey? This wouldn't stain up as easily as the white grout you had.

 

[Dave]

Hi, thanks for chiming in. Yes, absolutely we do. Even if it was occasionally missed, it never occured on the old tild/grout.
Could grout be a cause, reacting with something?

Thanks

What do you clean the tiles with.

 

[JustDave]

I dont know what's causing it, but you can get "Mapei Fuga Fresca" in various colours which is a grout reviver, but also you could chose a different colour to what you have at present and change that grout colour to a grey? This wouldn't stain up as easily as the white grout you had.

Thats a fair point about the grout colour and did think that too, but me being me, I'd know theres still an underlying problem. Thanks for the idea.

 

[JustDave]

What do you clean the tiles with.

Since it started happening, kept it quite simple. A 10% solution of bleach/water (approx) spray for bacterial/mould prevention and cleansing and on other days a white vinegar solution.

 

[Dave]

Since it started happening, kept it quite simple. A 10% solution of bleach/water (approx) spray for bacterial/mould prevention and cleansing and on other days a white vinegar solution.

Morning, using strong bleach can destroy the antibacterial properties of the grout allowing mould growth.

 

[JustDave]

Morning, using strong bleach can destroy the antibacterial properties of the grout allowing mould growth.

Oh, Is that too strong bleach ratio? Incidentally, looking at the Palace grout packaging, it doesn't state any anti-mould/fungal properties.
Could the brown discolouration be cause by some kind of mould/fungus?
The tiling was done by a professional but due to some circumstamces, I had to tackle the grouting and that was the grout he gave me.