For a cup of fluid? Leave it be.
It's pretty hard to change all of the fluid in a hydro. There will always be at least two cups, plus what is in any cylinders on attachments, that doesn't get changed short of total system disassembly. There is sufficient fluid in the reservoir to suitably dilute such a small amount.
There is no requirement to be quite so fastidious about the fluid level. It changes as the individual cylinders cycle in and out, as well as with fluid temperature. If it's within a half quart, call it done. A FEL will change the level by 3/4 of a quart or more between all cylinders fully extended and fully retracted.
It's pretty hard to change all of the fluid in a hydro. There will always be at least two cups, plus what is in any cylinders on attachments, that doesn't get changed short of total system disassembly. There is sufficient fluid in the reservoir to suitably dilute such a small amount.
There is no requirement to be quite so fastidious about the fluid level. It changes as the individual cylinders cycle in and out, as well as with fluid temperature. If it's within a half quart, call it done. A FEL will change the level by 3/4 of a quart or more between all cylinders fully extended and fully retracted.
