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I would like to circulate the water within an aquarium that contains around 30l water with a circulation pump and an active chiller that contains R134a cooling fluid. New water shall be sucked with a peristaltic pump that can build up a pressure of up to 15bar. I was thinking of mixing the chiller cycle with the peristaltic pump but I think this could be a faulty design as the peristaltic pump will pump into both direction of the chiller circle. Please see a schematic below. How would you realize the piping?

Further information as requested by @mart

  • Flow rate is around 100-200l/h from the peristaltic pump and 1200-1500l/h from the circular pump.
  • I don't know the head loss of the chiller, I contacted the manufacturer. It is a Titan600 from aquamedic. enter image description here
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  • $\begingroup$ what are approx flowrates for both flows? What's the operatin principle of the circulation pump? Are there excessivly long pipe runs? What's the headloss on the water side of the active chiller? $\endgroup$
    – mart
    Commented Jul 18, 2022 at 13:48
  • $\begingroup$ @mart added additional information. The piping of the chiller circle is minimal: below 2m. $\endgroup$ Commented Jul 18, 2022 at 13:51
  • $\begingroup$ thx. Your basic desin is sound. Are you concerned the peristaltic pump will run backwards with this setup? (It wont) what is your question exactly? $\endgroup$
    – mart
    Commented Jul 18, 2022 at 13:58
  • $\begingroup$ 1200 / 30 = 40 water changes per hour. A bit much? $\endgroup$
    – Solar Mike
    Commented Jul 18, 2022 at 14:10
  • $\begingroup$ How do you mean that the peristaltic pump will pump in both directions of the chiller cycle? A peristaltic pump pumps only in one direction. If the chiller is not operating, the peristaltic pump will push water in both directions on the T shown in the diagram. If the water is above thermostat temperature, the chiller will engage, but pressure differences may be problematic unless a directional flow valve is used. $\endgroup$
    – fred_dot_u
    Commented Jul 18, 2022 at 14:36

4 Answers 4

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Plastic tube is normally used for aquariums ( likely PVC). Should be fine unless there is some factor you did not disclose such as high temperature ,eg 50 C+. With flexible tubing could be routed in any convenient manner. Salt water aquariums commonly have chillers and occasionally automatic water addition to maintain level so very similar arrangements exist. PS; the circulation pump shown would have excessive capacity.

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  • $\begingroup$ I will use a 3/4" garden pipe. The circulation pump that will be used will probably be an EHEIM1200 or 2500. $\endgroup$ Commented Jul 18, 2022 at 15:32
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Active chillers such as those used to cool CO2 lasers have a pump built into the system. Additionally, you'll find a thermostat and the ability to regulate the temperature.

Note also that typical active chillers for lasers and milling routers are used in systems of substantially less volume than indicated in the edited post. This would not be a problem, but one should allow for increased time to stabilize the temperature. Additionally, if there is greater thermal loss from the aquarium than the chiller can replace, you'll have overall warming rather than cooling.

Increasing the flow rate with extra pumps will not change the thermal characteristics.

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None of this seems like a high pressure application, regular pcv plastic tubing should be fine. You might want it insulated.

The make up water can be piped in wherever you want. Does it matter which way it flows? Depending on where it is, it might be easier to just route to the tank directly.

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  • $\begingroup$ I would like the water to be mixed in a container or the T piece before because it is a requirement that the test water shall not directly be put in the aquarium. $\endgroup$ Commented Jul 18, 2022 at 15:31
  • $\begingroup$ @MarcoBobinger then put it downstream of the chiller. $\endgroup$
    – Tiger Guy
    Commented Jul 18, 2022 at 18:41
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Your basic setup appears sound. Regarding your concern, that the peristaltic pump might damage the circulation pump through back pressure: The peristaltic pump will, in this setup, not generate 15 bar of pressure, as long as the path from peristaltic pump to aquarium is open. The pressure at the T-piece will be static pressure + dynamic pressure as a function of flow rate from T-piece to aquarium and pipe length, thickness, etc. This wont be much. The low flow rate of the peristaltic pump will hardly change anything.

The peristaltic pump is capable of 15 bar, meaning it can deliver its rated flowrate against a pressure of up to 15 bar.

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