Good evening fellows. Tap water here during winter flows at mean temperatures of 4-6 Celsius degrees (near freezing point, that is). I usually avoid developing anything until April because I fear to cause mosaic effect on gelatin, not to mention the fact that the wash itself would be partly inefficient. However, this winter I have taken pictures of my sister, who's waiting a baby, so I'd like do develop the film immediately to make sure everything is OK and eventually take the pictures again. If I wait and - say - find out that the shutter was broken, I'll have no further chance to take these pictures once again. So this time I am compelled to deal with very cold water during wash. Let's suppose I start with a developer at 18 degrees (not the usual 20) and then wash at 4 degrees. Is this range enough already (with nowadays emulsions) to cause a mosaic effect? In case, what should I try? Would it be better to develop with a colder developer (say 14-15 degs.), or trying to rise the wash temperature with the heater (which usually causes cycles of cold and warm water around an avarage temperature, which may be worse for the mosaic effect)? Film is Ilford FP4 by the way. Thank you very much for reading.