You may (or may notI came across the post that you were talking about.
Bottom line is that it's a non-issue.
Show me a study that identifies the bacterial populations in our domestic hot water systems, then we can discuss any potential dangers from there.
The hot water heating loop setup is comparable to having a larger house that has longer runs for hot water supply to the drinking faucet. For that matter, once you turn off the taps, the water will cool down to room temperature anyways. I don't see any merit in that argument.:spin3:
To summarize the bacteria threat is present, but the fact that you're using an open loop might transfer the bacteria to your aquarium especially when the loop has been sitting unused for a long time [like in the summer].
Essentially the safest option is to use a heat exchanger and plumb the two loops separately.
You may (or may not) want to do a search of of the terms [legionnaires disease radiant heating] you'll find a lot of information out there about that.
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I've read through the rest of the thread that you linked, Raul, and it seems like people's concerns are mainly around the issue of the water sitting in the pipes for an extended period of time.
I would suggest as a solution that because the heating loop is made up of flexible pipe, that during the summer when tank heating is not required, that the heating loop be propped up out of the tank water and the controller be programmed to turn the recirc pump on for a 15 minute interval every 24 hours.
That would reduce the risk of bacteria building up in the system.
Put the heating loop back into the tank water when heating season returns.
That would be too cool a water temp if you plan on growing SPS.
Dave.M
I'm going to have about 1100g system total with a 625g DT can some one send me a link or a more simplified diagram of the closed pex system? There is no way I'm going to use 3 or 4 800 watt heaters that will never turn off and only add 50$ to my electric bill each month. The tank and system will also be in a basement. Plan on keeping the tank around 74-75 degrees
This thread has detail of one way:
http://www.reefcentral.com/forums/showthread.php?t=2232513