I like spirulina too. I used chlorella quite a while (6 months or longer), but have stopped, didn't feel it was helping me anymore.

The only time my kidneys really really hurt was when I was really really sick. They were so loaded with mercury they just about stopped functioning. they were real swollen and sore, I could literally feel them like two huge kidney beans in my back, I could literally feel the shape of them.

I used an herbal colon cleanse to get them moving, it did work. Every now and then I still get an ache or two, I am not sure if it's mercury or an old injury there or a combo, but I drink lots of water on those days and use a chelator, generally cilantro, sometimes DMSA. Also, zinc seems to help a lot, along with the usual calcium/magnesium. I take the occasional ache there as a sign that I am slightly constipated. I actually don't think I have any major permanent damage. I noticed Dmsa or cilantro (great fiber) will make me unconstipated too so there is probably a connection to mercury or something causing the kidneys to slow down, and the chelators do seem to help loosen it.

Also eating oatmeal for breakfast in the morning seems to help keep the kidneys happy (no constipation).