Looking for some experience taught wisdom... 

A relative of mine in West Michigan had a question on their new open loop geo system served by a well.  They opted to try open loop first not knowing the well water condition, but knowing that a closed loop might be required if the water quality was unworkable. 

The system is up and running great, but the water test came back worse than they hoped...

Well Report....
Iron =  1.02 mg/L
Sodium = 37.2 mg/L
Fluoride = 0.15 mg/L
Chloride = 74.4 mg/L
Nitrates all < 0.1 mg/L
Sulfate = 133 mg/L
Hardness (CaCO3) =  518 mg/L

After only a short time of operation (~1 month), owner is already seeing significant red staining out in the white pvc discharge drain pipe at the pond, where it gravity flows out.... and wondering if this water is damaging his coax heat exchanger.  This end (discharge) might expect more sediment/staining as it is not pressurized, correct? 

Questions...

1.  Is this water quaility "unworkable" for an open loop system? 

I've read on this forum that some have successfully operated pump&dump systems with some level of  iron in the water for some time (I believe it was a posting by "joe.ami", but in same and otherpostings are warnings about fouling the heat exchanger. 

2.  I seem to remember something about "baterial iron" being worse than just iron.... ?
 
3.  Based on the above water test results can one tell between the not so bad iron and the really bad stuff ?  

4.  If we are talking about (2) different things, can anyone give some general rule of thumb for low (safe to equipment), boderline, and high (dangerous to equipment) levels for each type of iron ? 

5.  Even if one knew it was the "not so bad" type of iron, are the levels above survivable... (in other words will not require cleaning of the coax every week)?  Cleaning more than once or max twice a year would be hard to swallow if it was me ?  

6.  Homeowner is not going to be excited about putting in a closed loop, but frequent cleaning for the next 20 yrs is very painful and a failed heat coax also painful (how much $ ? )

Any info, examples, counterexamples, or advice for this situation would be greatly appreciated.  

Posted By jonr on 21 Nov 2012 06:22 PM
They should consider installing something to measure COP to know if it is getting fouled.

I thought about that, but haven't checked yet to see what initial measurements were taken at startup.   How long does it typically take to confirm it is or isn't getting fouled ? Would that take a couple weeks, a couple months, or more like a couple heating seasons ?

Hardness will stay in solution when you cool the water (ie, winter). Iron is mostly effected by oxygen (typically not an issue in the closed part of the system with copper pipes).  
Water test report shows 10 mg/L iron.  How do you tell if the higher level of iron is workable or not?  If there is no "bacterial iron" or iron bacteria, can this level of iron be handled by periodic cleaning ?