How much fines should build up in your water box after half a day of pumping with healthy material cylinder and rams? I pumped a really wet mix and drained the water box quickly. Maybe a little bit in the bottom. I came back the next day it was all caked on the mud cups and on the chrome near the mud cup when I cycled it. And filled about 1/4 of the water box with grout turned into balls. Is this an issue ?  

I asked ConcretePumping.com AI and here is what it said.

Water Box Maintenance for Concrete Pumps

Based on your description, here's what you should know about water box fines accumulation:

Normal Accumulation

• Fine cement particles naturally accumulate in the water box as piston cups wear
• With healthy material cylinders and rams, you should see minimal accumulation after half a day
• The guideline is that once concrete paste reaches 3/4 inches from the bottom, the box should be drained and cleaned

Your Situation Analysis

What you're describing—material caking on the mud cups and chrome, plus 1/4 of the box filled with grout balls after a day—suggests:

1. The wet mix likely contributed to more material passing by the piston cups
2. The accumulation rate seems higher than ideal, which could indicate:
   • Possible accelerated wear on your piston cups
   • Potential issues with sealing between components

Recommendations

• Clean the water box thoroughly now to remove all accumulated material
• Keep the water box full during operation (always stop the pump before opening the water box covers)
• Monitor accumulation rate going forward - if you continue to see rapid buildup, this may indicate it's time for service
• Consider having your pump serviced if this becomes a persistent issue

Regular water box maintenance is crucial for cooling the differential cylinders and lubricating the rams properly.