reef-pi :: An opensource reef tank controller based on Raspberry Pi.

[dmolavi]

Looks very nice! Is that a reset button I spy?

Close...Power button.

 

[crusso1993]

Dry fit...LEDs don't come on but should be an easy thing to fix...

Smooth!

 

[Ranjib]

Wondering if anyone has tried this PH board. Sounds way to cheap to be trusted, but it even includes two temperature sensors (one on-board and one waterproof). Any opinions?
http://www.mini-kossel.com/Arduino-PH-Board

does not have galvanic isolation (i.e its prone to aberration)

 

[crusso1993]

Development work is humming along . Now that the pwm bug is sorted I am refocusing in ph board . We have the driver work done, and next is integration of calibration module and start doing field testing (need all of your help, who have pico board or ph board on this) ... it’s been constantly raining here in Bay Area , and I’m realizing having garage downstairs of our apartment, is a discouraging factor during such weather ...

On a separate note , I am big fan of Serpadesign youtube channel , run bay Tanib Serpa who shares a lot of good videos on terrarium /Vivarium/freshwater tanks. I built this native terrarium (more excuse to spend time with my son ) last month , it’s doing ok since then, and is blooming tiny flowers now . Me, wife, son everyone is intrigued and full of joy about it

Flowers

This looks pretty cool!

 

[b4tn]

Development work is humming along . Now that the pwm bug is sorted I am refocusing in ph board . We have the driver work done, and next is integration of calibration module and start doing field testing (need all of your help, who have pico board or ph board on this) ... it’s been constantly raining here in Bay Area , and I’m realizing having garage downstairs of our apartment, is a discouraging factor during such weather ...

On a separate note , I am big fan of Serpadesign youtube channel , run bay Tanib Serpa who shares a lot of good videos on terrarium /Vivarium/freshwater tanks. I built this native terrarium (more excuse to spend time with my son ) last month , it’s doing ok since then, and is blooming tiny flowers now . Me, wife, son everyone is intrigued and full of joy about it

Flowers

Funny, but the other day I saw a terrarium at target and thought to myself how cool it would be to make one. Couple days later I took my son to a comic book store and they had some really cool Star Wars figures that you paint and I got this brilliant idea to make a terraiam with a battle of Endor theme. I thought it was a super original idea till I googled it lol. I’m still planning on doing one.

 

[bishoptf]

I know we talked about this earlier in the threads but want to get some additional information. Currently running my heaters in failsafe mode, thermostat in the heater is set and reef-pi is used as failsafe if they go out of range on the high side. One of my heaters is not adjustable, it's pre-set to 78deg, I want to lower the temp in the tank to 74 and to do that I would need reef-pi to control the temp. That would require the relay to be used more frequently, I think I remember that it shouldn't be an issue since the relays should have a decent amount of life but wanted to get some input before making the change.

Thanks!

 

[Mikeneedsahobby]

I know we talked about this earlier in the threads but want to get some additional information. Currently running my heaters in failsafe mode, thermostat in the heater is set and reef-pi is used as failsafe if they go out of range on the high side. One of my heaters is not adjustable, it's pre-set to 78deg, I want to lower the temp in the tank to 74 and to do that I would need reef-pi to control the temp. That would require the relay to be used more frequently, I think I remember that it shouldn't be an issue since the relays should have a decent amount of life but wanted to get some input before making the change.

Thanks!

I changed the frequency of temperature checks to every 10 minutes. At that frequency I still hold +\- 0.3 degrees but the relay is switching less often. I probably could go longer between checks.

 

[bishoptf]

I changed the frequency of temperature checks to every 10 minutes. At that frequency I still hold +\- 0.3 degrees but the relay is switching less often. I probably could go longer between checks.

Thanks thats nice data to know, how many gallons is your tank? This is a very small tank 2.5 gallons, I probably should have mentioned that. Not sure how much of a swing but something I can test and see how much it swings over a given time.

 

[Ranjib]

I know we talked about this earlier in the threads but want to get some additional information. Currently running my heaters in failsafe mode, thermostat in the heater is set and reef-pi is used as failsafe if they go out of range on the high side. One of my heaters is not adjustable, it's pre-set to 78deg, I want to lower the temp in the tank to 74 and to do that I would need reef-pi to control the temp. That would require the relay to be used more frequently, I think I remember that it shouldn't be an issue since the relays should have a decent amount of life but wanted to get some input before making the change.

Thanks!

An average electro-mechanical relay lasts 1000,000 cycles. If we assume it lasts at least 500,000 time (half the expected cycle), and if you are running temperature check at 1-minute interval, then its 525600 times a year. So safely a year at least. You can get higher rating relays, increase temperature interval etc.

Get an understanding of how long it takes for your heater to increase tank temperature by 1 degree. And then decide on how much fluctuation you are planning to permit.. together those two should give you a fairly good check interval, .. be conservative and use something lower than that value

 

[b4tn]

I know we talked about this earlier in the threads but want to get some additional information. Currently running my heaters in failsafe mode, thermostat in the heater is set and reef-pi is used as failsafe if they go out of range on the high side. One of my heaters is not adjustable, it's pre-set to 78deg, I want to lower the temp in the tank to 74 and to do that I would need reef-pi to control the temp. That would require the relay to be used more frequently, I think I remember that it shouldn't be an issue since the relays should have a decent amount of life but wanted to get some input before making the change.

Thanks!

You could also just use a solid state relay for the heater control. then you don’t have to worry as much about mechanical failure. I’m going to eventually build another power box with a mix of mechanical and solid state relays for things that switch often like ATO and heater. The standard ssr relays you see would not support a heater but this one will.

https://www.amazon.com/dp/B07JYLQPC8/ref=cm_sw_r_sms_c_api_i_szIHCbC5T51AX

 

[Ryan115]

You could also just use a solid state relay for the heater control. then you don’t have to worry as much about mechanical failure. I’m going to eventually build another power box with a mix of mechanical and solid state relays for things that switch often like ATO and heater. The standard ssr relays you see would not support a heater but this one will.

https://www.amazon.com/dp/B07JYLQPC8/ref=cm_sw_r_sms_c_api_i_szIHCbC5T51AX

@Tom Bishop I agree that a SSR would be the way to go, since you will likely be looking at short cycles on a small tank. However, I imagine on a tank that size you are running a fairly small heater (<75W), so I think that you would be fine with a regular SSR on something like this https://www.sainsmart.com/products/4-channel-5v-solid-state-relay-module . They are rated up to 2 amps, so smaller heaters and many current pumps would be ok as well.

 

[Mikeneedsahobby]

Thanks thats nice data to know, how many gallons is your tank? This is a very small tank 2.5 gallons, I probably should have mentioned that. Not sure how much of a swing but something I can test and see how much it swings over a given time.

Yep. You will be switching on/off a lot more frequently than me. I have 75 dt and another in the 20 sump. You can still experiment with different check times to tune the temperature swing.

 

[bishoptf]

Thanks for all the input, lots of good information provided, will have to think about the best path forward. Another option is to get a new heater that allows me to set the temp level and continue running reef-pi as a failsafe. I've had this heater for over a year but they only run at most 6 months out of the year.

 

[Ranjib]

It’s hard to get solid state relays with high amp rating. The ones I had almost always rated for 2 amp. Yesterday I read through some more documents on this, and the learning was these specs are for max load, for lower loads the lifespan should be much higher , multiple of millions on/off

 

[bishoptf]

It’s hard to get solid state relays with high amp rating. The ones I had almost always rated for 2 amp. Yesterday I read through some more documents on this, and the learning was these specs are for max load, for lower loads the lifespan should be much higher , multiple of millions on/off

Just so I make sure are we talking the solid state relays or the ones in the DJ enclosure?

 

[b4tn]

Just so I make sure are we talking the solid state relays or the ones in the DJ enclosure?

He is talking about mechanical Relays I didnt know that a lower load increases lifespan. Thats good to know. A SSR has no mechanical moving parts so it will last dang near forever or at least much longer that a mechanical relay.

 

[bishoptf]

He is talking about mechanical Relays I didnt know that a lower load increases lifespan. Thats good to know. A SSR has no mechanical moving parts so it will last dang near forever or at least much longer that a mechanical relay.

Thanks good to know, even at 100w that's only about 800ma, will still need to think how I want to move forward, as always lots of good information.

 

[Ranjib]

He is talking about mechanical Relays I didnt know that a lower load increases lifespan. Thats good to know. A SSR has no mechanical moving parts so it will last dang near forever or at least much longer that a mechanical relay.

Not necessarily. As I was telling you, I spoke to multiple folks in makerfaire (some of them run a 26 foot mechanical giraffe made of iron and steel) and in different forums. Mechanical relays are cheap, available for higher current ratings, and can lust 3-5 years if you use it in its sweet spot. Solid state relays can go bad not due to mechanical wear and tear, but due to heat and other load related issues.

As rfc 1925 , point number 8 states, "It's more complicated than you think"

 

[bishoptf]

Not necessarily. As I was telling you, I spoke to multiple folks in makerfaire (some of them run a 26 foot mechanical giraffe made of iron and steel) and in different forums. Mechanical relays are cheap, available for higher current ratings, and can lust 3-5 years if you use it in its sweet spot. Solid state relays can go bad not due to mechanical wear and tear, but due to heat and other load related issues.

As rfc 1925 , point number 8 states, "It's more complicated than you think"

And I thought I was one of the few that got into the weeds with stuff, you start reading rfc's that's getting into it.

Some data from my testing so far, 2.5g fluval spec, planted. House is a little warmer today since the sun was out and the ambient is around 70deg. Tank peak started at 78.45 and it took about 30min to drop .5 deg. I have my temp checking every 60s. It may be a little faster if the house was cooler but I think it shows that my on/off cycles shouldn't be to bad. Since this is my shrimp tank I do not need to keep the temp range super tight, 1 to 2 deg should be good enough.

 

[Bigtrout]

There is a reason that even in half million dollar cnc machine that most of the relays are still mechanical. Solid state relays do have their place, but to implement them properly takes good heat sinks and good circuit planning.