critique my DIY automatic water change system

[walkerbrody]

This is a terrible paint picture of my diy automatic water change system.
I have a 10 gallon area in my sump that is slightly higher than my skimmer section. During normal opperation a small pump circulates roughly 100gph through the water change section.
I have a 7 day timer than turns on a 12v power supply.
During non-water change conditions the normaly closed section of a dpdt relay powers a second relay. The normaly closed circuit of the second relay turns off the 100gph recirculation pump for the water change section of the sump. When the float switch is in a low or open-circuit position the relay goes to the open circuit section. This section powers the new saltwater fill pump until the float switch closes the circut.
When the 7 day timer turns on the 12 volt power supply (for 5 minutes per week) The first relay turns off the second relay (the one that controls either the recirculation or the new saltwater fill pump), and turns on the drain pump. The drain pump empties the water change area of my sump at roughly 1.7 gallons per minute.
All recirculating and refilling lines are above the water level to prevent syphon. The drain line is above the water level also to prevent syphon.
Water pipes are shown in black (so is the tank baffles and pumps, sorry)
and the electrical system is in red. I know my drawing is terrible, but the system seems to work well.
I would appriciate any feedback if you can understand my mess lol. Thank you

 

[Troylee]

Don't see any pics???? Lol

 

[walkerbrody]

hmmm there were some... ill see if i can fix it lol

 

[walkerbrody]

hell now the picture is showing up twice, but you can get the idea lol

 

[Paul_N]

It just seems you will end up topping off with saltwater when you lose water in the sump due to evaporation which will cause your SG to rise.

 

[walkerbrody]

I have an auto top off in the return section. The water level of the water change area remains constant due to a gravity overflow. The recirculation pump for the water change area stops before the pump removes any water from the tank, which excludes the area from the rest of the tank until after the water change process has finished.

 

[melev]

I don't see any pictures.

 

[walkerbrody]

Ill add them again. I cant believe i got a response from melev. I am starstruck. lol

 

[walkerbrody]

 

[melev]

Looking over your pictures now. :)

 

[melev]

From your first post and the latest images, I'm getting the impression the water change zone is always full with the current water in the system, but when the water change commences, no water is added to that zone for the time being. It pumps out, then new water goes in from the reservoir until it is full, then the water change system goes dormant and water begins recirculating into the sump zones once again. Right? Seems like a pretty good failsafe, assuming your new inbound water never fails to shut off. If it does, the sump will overflow with excess saltwater.

I'm going to be installing my own automatic water change system in about two or three weeks. That'll be nice, having it do a small daily water change and never lift a finger again. :)

That's your plan, right?

 

[walkerbrody]

That is the plan. I have my back up switch for the ato wired so that it cuts power to the saltwater fill for the water change system in the event that the switch in the water change area fails. It has been running for 5 weeks now with no change in salinity. At first i planned on small daily water changes but I was told larger weekly ones would be more efficient for nutrient export.

On a personal note. Your reefcast podcast with quicksilver from 2006-2009 got me reinterested in the hobby. Your melevsreef website showed me how to design and build my own sump, and the importance of a refugium. I have built dozens of sumps for friends and reef club members because of what I learned from you. The effort you have put into teaching others the reason for my success and enjoyment of this hobby. I greatly appriciate all the help you have given me.

Thanks again, Brody Walker

 

[melev]

That is the plan. I have my back up switch for the ato wired so that it cuts power to the saltwater fill for the water change system in the event that the switch in the water change area fails. It has been running for 5 weeks now with no change in salinity. At first i planned on small daily water changes but I was told larger weekly ones would be more efficient for nutrient export.

On a personal note. Your reefcast podcast with quicksilver from 2006-2009 got me reinterested in the hobby. Your melevsreef website showed me how to design and build my own sump, and the importance of a refugium. I have built dozens of sumps for friends and reef club members because of what I learned from you. The effort you have put into teaching others the reason for my success and enjoyment of this hobby. I greatly appriciate all the help you have given me.

Thanks again, Brody Walker

For your water change system, you might consider a timer on the whole assembly that kills power to it so it can't run non-stop if the float switch doesn't trigger the cease point. Like 10 minutes, no matter what, it shuts off.

You'll find a few more podcasts on ReefAddicts.com, my other site. Lots of documentation has been amassed over the past 1.5 years on that site, and melevsreef is getting a massive facelift currently.

 

[revhtree Verified Admin]

Ehhh what does Marc know besides everything? Exactly. LOL!

 

[walkerbrody]

I was considering using a one shot timer relay like this one Retriggerable One-Shot Timers on American Control Products Div., Precision Timer Co., Inc.. I figured I could add it onto the system in the future if I had any issues. Is this what you have in mind?

I forgot about the reef addicts website. I greatly enjoy that site also.

 

[melev]

I'm not very good with electronics and specifically relays. I never tried to learn that stuff to the point that it would make sense to me, so i rely on others to help me with that kind of decision making. What does the one shot do? Sounds like a good default to make sure it doesn't run repeatedly, but that's all I understand so far.

 

[walkerbrody]

Im not great with electronics either. I started researching them when I was thinking through options to make the water change work. To my understanding when the signal voltage is sent (by the 12v power supply connected to the 7 day timer in my case) it triggers the timer in the relay to start. When it starts it closes the circut on the relay for the length of time the relay is adjusted to. After the preset period of time the relay opens the circut and resets the timer. The one shot relay wouldn't allow the circut to close again until the 12v signal source is turned off and turned back on a week later. I could use the float switch after the relay timer. The float switch would stop the water flow when the water change area is full, but the circut would only be open for the maximum amout of time allowed by the one shot relay incase the float switch failed.

 

[melev]

I'll defer to others that know this stuff better. It sounds like you are on the right track.

With my system, I want to draw between 3 and 8g out of my 250g's worth of saltwater. I'm trying to make sure I don't accidentally draw out all of it in one massive failure. It's a tricky design but I think it will work. I bought a neat machine to suck the water out of the tank while adding new saltwater in, but where to put it and where to run the tubes has been a little confusing. I need to order some stuff from Savko, so I figure I won't get around to this for two more weeks still.

 

[walkerbrody]

The easiest option I found would have been to purchase a spectrapure litermeter and a remote unit to precisely remove and return a precise volume of saltwater. I couldn't afford the $600+ for the convience of not changing the water by hand. Then I was going to try a dual head perlistic pump, but couldn't find one for what i wanted to pay. So i decided to attempt it with a few extra pumps and a couple $3 ice cube relays.

 

[melev]

That's what I bought, the dual head peristaltic pump. I got a great deal on a lightly used one. They retail for $1400. Tubing for that pump is extremely expensive, but I hope to use something I found at Home Depot instead.