Reef Safe Material for Water Cooling Block

[JerryDryEmOut]

Hello all,
I am an electrical engineering student working on my senior design project. I have decided to design an automatic water change system utilizing Peltier elements for temperature correction of incoming water. I am having trouble finding a material that is reef safe to use as a cooling block. I know that most normally used materials (aluminum, copper, etc.) corrode in salt water and cause all sorts of problems. Any ideas would be greatly appreciated, thanks in advance.

 

[Gtinnel]

I’m not exactly sure what you’re wanting but I believe titanium is one of the few reef safe metals afaik.
Also, is it just for proof of concept because for an AWC one of the advantages is that the new water doesn’t need to be heated because you’re not replacing a lot of water all at once.

 

[redfishbluefish]

I agree with @Gtinnel that if it has to be metal, titanium is your best choice. Also note that most folks that use automatic water change systems do daily, relatively small volume, water changes that don't need heating or cooling. The volume of the water change is so small compared to total tank volume that heating or cooling isn't necessary.

 

[JerryDryEmOut]

I’m not exactly sure what you’re wanting but I believe titanium is one of the few reef safe metals afaik.
Also, is it just for proof of concept because for an AWC one of the advantages is that the new water doesn’t need to be heated because you’re not replacing a lot of water all at once.

Do you know of any manufacturers that produce small titanium cooling blocks? I am a little worried about the cost. After doing some research it seems like 316 stainless (commonly used for marine applications) should be an acceptable subsitute?

As far as the temperature correction is concerned I included it since I find that I often need it during the summer months. The air conditioning in my house can't keep up when it's 118 F outside and the temperature in the house gets to the mid 80's. Even at night, the water in my mixing barrel (which is located outside due to space concerns) is 90+ F. When I'm already pushing 80 degrees in my tank doing a 30% water change (even very slowly) has drastic effects on my tank temperature. The major benefit of Peltier elements is that they can both heat and cool depending upon the direction that you pass current through them.

In the end, whether it's efficient or not I have a minimum level of complexity to meet for the project and two pumps that pump water in/out of the tank do not meet that level of complexity. The system will be configurable to change water based on a selected time, volume, or position of a level switch in the makeup barrel. It will measure the temperature in the tank, makeup barrel, and effluent of the cooling block and use a custom PID equation to modulate the on/off time of either the pumps or the Peltier elements as necessary for temperature control. It will have a series of level switches and an audible alarm, the level switches will check for an abnormal condition (sump level variations, makeup barrel empty, etc.) and will trigger an alarm if an abnormal condition is detected. Everything will be controlled with a Tiva arm cortex microcontroller utilizing a 128x128 dot matrix display for indicating progress and measured temperatures as well as a keypad for user interfacing.

 

[JerryDryEmOut]

I agree with @Gtinnel that if it has to be metal, titanium is your best choice. Also note that most folks that use automatic water change systems do daily, relatively small volume, water changes that don't need heating or cooling. The volume of the water change is so small compared to total tank volume that heating or cooling isn't necessary.

Any ideas on how to go about getting a titanium cooling block without paying a fortune for it? I recognize that not everyone needs the ability to heat or cool incoming makeup water but in this case, I do. Please refer to my reply to @Gtinnel for a more detailed explanation.

 

[redfishbluefish]

Pump the water through a chiller, which already has the titanium element. And yes, costly.

 

[JerryDryEmOut]

Pump the water through a chiller, which already has the titanium element. And yes, costly.

But a chiller can only reduce temperature, it cant heat as well. Also, temperature control is the most complex subsystem of the project and is required to meet the complexity requirement.

 

[elysics]

Well if it's only for the grade and doesn't have to work particulary great longterm, you could coat a stainless heat exchanger with thin rubber or something. Could be its own chapter in your report cost/benefit wise.

And from your description, nothing about that sounds like it is specific to reef tanks or even saltwater tanks.

So if reef safe is too expensive for you, maybe just drop the reef part, at least regarding the cooling unit.

 

[BaliReefBox]

I used peltiers on a fresh water system and they were a waste of electricity...the cooling efeect wasnt up to the task and with 4 peltiers would only drop the temp by about 1C.... maybe if you can get an old water cooler/dispenser you may be able to get the parts from there... I did buy a titanium hip flask for a reasonable price it wont have the internal channels but maybe you can sort something out

 

[KStatefan]

Do your project using fresh water for proof of concept

 

[elysics]

I used peltiers on a fresh water system and they were a waste of electricity...the cooling efeect wasnt up to the task and with 4 peltiers would only drop the temp by about 1C.... maybe if you can get an old water cooler/dispenser you may be able to get the parts from there... I didnt buy a titanium hip flask for a reasonable price it wont have the internal channels but maybe you can sort something out

Not all peltiers are the same you can definitely get more than 1°, especially if you put a secondary cooling loop on the other side of them.

I wouldn't want to pay the electricity bill for that though, but for a graded project, why not