Do you know how many prints this tanks are suppose to last before you change them. I have print some 100 prints with them and now they are giving me more trouble, do you think is time to change them?

It depends on what printer you're using and how many tanks/cartridges it uses but 100 sounds like a lot to me (GFY) so it may be time for a refill or replacement. I think a 4 cartridge is only supposed to get 60-80 prints.

I've heard that you should only refill the tanks 4 times and then replace. I guess since they are more prone to clog. Mine are starting to clog as well so I was going to go ahead and replace them.
Lara

I recently purchased a new Canon IP3000, (found on ebay) and ordered the cartridges. It certainly appears to be new, but the printer wouldn't automatically align the printhead. My printing comes out with lines on it. Has anyone else had problems with clogging right from the start?

I haven't but sometimes the inks haven't settled from shipment. If you let them set in the print head for a day or so, maybe it'll improve. Otherwise, you might try a print head cleaning.

I got mine new and is been difficult since the beginning, it clogs a lot, but at some point it has done it more frequently, so I guess is time to change... I got the epson so is $75! for a new set.. oh well

What kind of Epson do you have? My dad gave me the idea of using a syringe to clean out my print head and it works great! I fill a syringe that I got at wal- mart with my son's prescription, it doesn't have a needle just a long tube on the end to get down into the bottle of medicine. Anyway it fits perfect over where the ink gets drawn in. I have used it a couple times with warmed vodka and it has cleared it right up. I just keep running my nozzle check to make sure the ink is coming through.

I have an Epson too and KopyKake told me that the refill cartridges that they sell will work. They aren't as expensive as the cartridges themselves.