There is nothing feasible that you can do. The iron is going to oxidize out of solution when it come into contact with oxygen. There are chemical sequestering agents available for water treatment, but it is not going to be feasible to add these chemicals to a sump.
It is probably a good idea to oversize the french drain to lengthen the time between cleanouts.
We monitor the Bath Hot Springs system in the UK and the level of iron precipitation is horrendous, particularly for all the monitoring equipment!
The only way this is dealt with is by the ongoing program of cleaning and maintenance. Regular monitoring of your drains for the first few months (year?) would give you an indication of precipitation build-up times, which you can then apply to a maintenance program.
If only it were different!
Adam Beresford-Browne
Zenith International Ltd
zenithwater.com
I don't pretend to know anything about this case, but is it possible to install some kind of sacrificial anode similar to what is used in water heaters?
Unfortunately, since the material precipitates out of the water upon contact with air; there is no way to make a sacrificial anode. The only way to deal with the problem is by cleaning, either chemical or mechanical.
bmir is on track....I have fought this battle and found that chemicals can work but also try to eliminate any points in the system where air can enter in. I had a real problem with a couple of monitoring wells and by simply installing new concrete pads around the wells and adding new caps it seemed to help.
