I've not used Miele's tub cleaner and I have a SQ TL, but I usually clean my tub with dishwasher powder. Ecover, Trader Joe's and Seventh Generation all make unscented powder dw detergent. For me, it works well, but I've not used the Seventh Gen powder myself. I just know they make an unscented one. I buy my Ecover powder on Vitacost as that is only place I can find it in powder form--it is widely sold online elsewhere in the pods/packs, which might be just fine for your small Miele. You could use the extra packs in your dw if it works well with your water chemistry.

Using citric acid also works to clean the wash tub. I order mine on Amazon, but you can buy smaller packets of it in the canning section at the grocery store. Again, might be the right size for your Miele.

I've used Glisten liquid washer machine cleaner and it seems to work well, but it has an odor that I'm not fond. Dosing directions are rather vague and I probably use too much or not enough, each time.

Citric acid like SeaSea suggested. Or possibly cream developer that is used to activate hair coloring??

Salon Care 20 Volume Cream Developer ingredients:

WATER ,HYDROGEN PEROXIDE ,CETEARYL ALCOHOL ,CETEARETH-20 ,CETYL ALCOHOL ,STEARIC ACID ,PHOSPHORIC ACID ,TETRASODIUM EDTA ,ETIDRONIC ACID

from Sally Beauty Supply & other beauty supply stores

Avoid the Tide washing machine cleaner. It is awful.

Lemi Shine makes an unscented cleaner. Or as Sea Sea said, you could use dishwasher detergent. A powder dw detergent would be ideal. 1/3 to 1/2 cup should be enough. Or you could use the same amount of citric acid or about a cup of vinegar.