k, couple of things:

First, who's that girl in the picture? Second, your meter could be off so make sure its calibrated. Use EC readings instead of TDS. TDS is actually EC in micro siemens X 600 - 700. As such certain nutes manufacturers will tell you different TDS readings based on the most popular meters. BUT, the EC will always be the same!

So I assume what you are doing is adding the recipe and not getting the reading on the recipe label. If all else is accurate than don't worry about it, heres what you do:

Mix up the batch and feed it to them. Check the EC for a week, every day. If the reading goes down, increase your nutes on the next run. If your nutes are going up, then it was too strong for them and mix less next time.