Sounds like too much water in the mix, an incorrect mixing process, or too much water used in the grout removal phase. Grout needs to be relatively thick, like peanut butter. It also needs to rest a bit after the initial mix (slake) and then be mixed again before applying. Minimal water needs to be used in the grout removal phase but with frequent cleaning of the sponge and change of the water to clean. If any of these steps were done incorrectly, you could have the results you are describing and your grout will be weak and eventually crumbly.

Have you tried posting your question on the john bridge tile forum? They are tile experts over there and very helpful. You might even be able to search and find an answer without posting. I know that when we mixed our grout we used distilled water to avoid the white crud (I think there's a name for what you're describing, but I can't for the life of me remember what it is, but again, they will know at john bridge). We even used distilled water for the grout removal. We still had a tiny bit of white on the surface (our grout was chocolate brown, so any white showed), but I was able to get it off pretty easily using distilled water and a toothbrush. It sounds tedious, but it went quickly.

As far as the uneven grout color, I think LWO hit the nail on the head that it's also a water problem. Maybe some of it was mixed with more water than the other?

Good luck! I hope that you get this resolved to your satisfaction.

Here is a link that might be useful: john bridge tile forum

Effluorescence isn't usually a new tile problem. It happens bit by bit as the salts leach out due to the moisture content of the substrate. It could be a bad batch of grout, but poor installation practices are more likely. Do you have any leftovers of the grout? Mix a bit up yourself to the correct consistancy and spread it out onto the back of a tile and let dry. See what it looks like after drying. If it looks the same as the applied grout, ocntact the manufacturer from the contact info from the info on the bag.

Great answers! Thanks to everyone. I will be sharing all of this with my KD & hopefully we will get a good resolution.

Can you tell us how this was resolved?

I just did my bathroom tile last night, I chose Mocha, very dark chocolate in color. The grout lines are a gray. It's ok, but this is not what I wanted, at all.

Would love to hear how it was handled.

Thanks,
Bee

Not to change the topic but we had tile installed by a reputable experienced installer 12 years ago. We had just moved into our first house. I was not happy with the discoloration of the grout so I asked him to clean it. I went visiting with my new baby and toddler. Came home and found the grout more to the color I was expecting but...he had cleaned with muriatic acid (maybe full strength?) and every metal item on the first floor of my home was discolored. Stove, pots, door hinges, Thomas the tank engine toys, etc. pitted and various degrees of discoloration. Ruined.
We called our insurance company and they covered the replacement cost of everything. $$$$$. The insurance company dealt with the installers
insurance company. We never talked to him again. This is not meant to
scare people but it took a toll on me and I wouldn't want it to happen to
anyone. We were new homeowners and we trusted our tile contractor.

Were you able to resolve the issue? Can you share the resolution? I am having the same issue right now. The grout looked great yesterday before I went to bed. Now the chalk lines in all the grout. Thanks!

Hi, as a retired tiler of 25 years experience I can tell you of three grout discolour problems. Firstly however I observe that there are a number of different types of tile grout out there, and each has to be mixed, applied and cleaned up in its own way. If your tiler is an experienced tradesman he or she will know how to mix and apply the product selected. For instance, conventional portland cement based grouts can me mixed either thick or thin - from tooth paste like consistency to pourable like cream, and can be cleaned up without over concern about how much water you use or whether the clean up water is kept fresh or not. These grouts are probably the most fool proof, but will allow efflorescence to develop over time on say shower walls and floors.

Grouts based on an aluminum version of cement must not be mixed too thin, rather like tooth paste, and MUST NOT be cleaned up with lots of water - the dryer the better on the sponge. Two problems I have encountered with these grouts is that if mixed too thin so as to allow troweling on rather than applying with blades and spatulas the resultant grout will be chalky and weak. I also had one job where the grout (a light grey) was patchy on drying. Consultation with the importer threw up a number of suggestions such as contaminated mix water (but why did every batch show strong variation within each batch, rather than a consistent discolouration for each batch) and inadequate mixing (definitely not as I had used the same procedure with a very great number of jobs over many years without this colour variation). Tried using store bought water - same outcome. Dud batch possibility, but the grout colour is a very popular one and the importer had had no other complaints, or so he said. Then took notice of a very stubborn waxy coating on the tiles. This was a Chinese practise to prevent the tiles being damaged in transport and handling. Tile suppliers variously reported problems getting this wax off on completion of the job, but that is another issue. The possibility was that the wax was interfering with the grout, in some way. Provided samples of the "contaminated" grout to three firms who all swore they could find out what the contaminant was, but all subsequently ran for cover and provided no analysis. In the end I cut all the old grout out (130 sq meters of it) and replaced it all with epoxy grout. Problem gone - happy customer - wiser tiler.

This brings me to the third type of grout I am familiar with and that is the epoxy grouts. They are two part, need precision in mixing, and must be applied with steel blades rather like say putty. Clean up is with ample water - the more the better. Most tilers hate epoxies because they are considerably more work to apply. They have the virtues however that the colour as applied is the colour you wind up with, and they are waterproof and so will not cooperate with efflorescence and will not harbour moulds or stains. Great for bathrooms and kitchens. Ideal? Not quite. The white version of everyone's epoxy slightly yellows with age, and not uniformly. All other colours seem to be "colour fast".

As to your problem I suggest you try one of the paint on epoxy grout colourants. These can work really well but you need a test area to see if it does OK over the old grout. An easy job for a home owner to do - just follow the instructions. The epoxy colourant will also help with efflorescence because it helps close up the porosity in conventional grouts.

Failing this the only fix it to remove all the old grout and replace with epoxy grout. That definitely is not a home owner's job. Sorry. Hope it all works out.