Streaking and blobs with my CISS - help??

[speedracer]

I have an Epson NX415 printer and purchased a CISS system from a vendor on ebay. The unit is a 'no name' unit but seems to be built fairly well - flexible silicon(?) tubing, resettable chips (they work) and installed fairly easily. It has been working fairly well considering I had been removing, filling, re-installing and then charging the ink on the individual cartridges =Pain in the butt. My problem is every now and then when I print about a 100 or so pieces the printed text looks like it has run out of ink in that its splotchy and missing in areas on the lines. I know the outside ink tanks have ink in them so it can't be 'out of ink.' Also, when I first start printing for the day, if I don't do a head cleaning then the printing seems to take on this same appearance. Once the head cleaning is done then it seems fine until the next occurrence. I find it unusual that head cleanings must be done every day and after a certain number of printings- is it?? I have also noticed an occasional streak(s) and blobs on the paper again in BLACK not the other colors. The outside ink tanks are on the same table as the printer so they are at the same level. Ink level in the external tanks is at half. I have added a line to remove the waste ink to a separate container I mention this but I doubt is has any bearing on this problem but I did want to state it just in case...I have run about 2 bottles of each color ink thru the system since I first installed it so it is metering ink into the internal tanks. Any ideas???