Masterflex Dual Head - AWC - Unmatched Flow

[elFloyd]

In May I set up a Masterflex Dual Head pump for water changes, exchanging 2.5 Gallons per day.

In June I noticed my salinity was slightly increased. First thought was evaporation from the fresh salt water tank, so I started monitoring FSW salinity daily, and was especially careful to get the right salinity when making new FSW. No problem here, but I still saw a very slow salinity increase in the display tank.

Today I looked at the Apex graph showing off/on of the ATO pump, and noticed it stayed off about 8 hours after a water change. ATO normally comes on for about 10 minutes at two hour intervals.

I then checked the In and Out flow from the Masterflex pump. Over a two hour period the pump added 2.25 gallons of fresh salt water, but only removed 1.5 gallons.

I reversed the water lines.... same results, then I swapped pump heads... same results.


Here are the run lengths of the 1/4" tubing:

New salt water: FSW (10') > pump > Sump (50')
Old salt water: Sump (50') > pump > Drain (10')

At this point I can only assume the Masterflex pump heads are unable to push/pull equally when the distances are not equal.

Anyone experienced this?

[Breadman03]

Look for an adjustable occlusion head. Having one will allow you to adjust it to match the flow rate of the fixed head.

[elFloyd]

That's an idea!