Setting up automatic PWC's

[jherrin215]

I am in the processing of designing and building a set up for automatic PWC's. I want to get this to where the only things I have to do are have the saltwater mixed and flip a switch and push a button. This will all be controlled by a PLC setup in the basement. My only problem is how to get the water out and back into the tank. I am going to have my sump setup in the basement, which will make auto topoffs simple. I really don't want to have a pump staying in the tank all the time just for the PWC's and I definitely don't wanna have to put one in and out everytime. I was wondering if I could set it up where the water from the ov erflow goes down the drain during the PWC's. I could set it up where it would pump the majority of the water out of the sump into the main tank. The water that goes out the overflow would be garbage. When all the water is finished running out of the over flow I would then pump the new water into the sump. Then power back up the return pump after it gets enough in it to start the tank back to overflowing. Does anyone see any problems with this set up?? Do I need to draw water directly from the tank and put the new water directly back in the tank or would using the overflow and sump work ok??

 

[ccCapt]

Talk about automated! A PLC controlled system would be awesome. I'm assuming you are looking at using soleniod valves? I'de like to see what your plan looks like. Just remember, you're going to need equipment that can take the beating saltwater will give it.

 

[jherrin215]

Yeah, I am going to be using solenoid valves. I work in industrial maintenance and am pursuing a career in engineering and think this is gonna be a very fun project!! Can't wait to really get the ball rolling.

 

[fijiwigi]

That is really a great idea. Sounds like a good plan. Personally I just use a 2gallon jug with a drip to dispense some RO/DI water into my tank and I refill the jug every 3days for top-offs and the PWC I am still using a 5gal bucket I wish I could think up a simpler way that works for me.

 

[CatatonicBug]

I can see this in my head...
The Sump has baffles, so what you can do is use the overflow area from one side of the sump to the other as a dividing line. Use two identical pumps at the same time, on the same switch. One sucks water out of the side of the sump that comes from the overflow from the tank, while the other pumps new water back into the other side of the sump, acting as though the water was actually flowing over the baffle wall.

When you turn the pumps on, the tank water stops flowing over the baffle wall, and as soon as you turn them off, the water regains it's normal flow. I hope that makes sense...

 

[Kurt_Nelson]

Don't forget that while automating the PWC process is great, part of what I think really helps during water changes is siphoning off the rock. I run my siphon tube all over the nooks and crannies of the rocks, sucking out nasty stuff before it gets a chance to turn into nitrates. Changing the water is important, but don't neglect the basic tank maintenance too.

 

[pat8you]

Sounds like an interesting project. Keep in mind that the water level will lower in the sump as opposed to the main tank if you have an overflow system. So make sure you don't pump out so much that you run the pumps in the sump dry. So water volume taken out would have to be sump minus the level of water required for the pumps. Might need a big sump to do a decent water change depending on the size of the tank.

Edit: If your a T- ball valve on the return from the main tank to the sump then the existing pump in the tank will pump your water out for you. Then run a line from your new water to the sump and have a pump that is in the bin holding the clean water. So that way you would just twist the T-valve to divert flow and then plug in the clean water pump. Might be simpler and cheaper then buttons and switches.

double edit: you could also put a T-valve on the pump in the clean water container that way you could twist that one to flow in the container so that it mixes your salt for you when your making a new batch. (sorry also an engineer... a good project always gets us talking)

 

[jherrin215]

I want to have a y on the overflow to sump line. 1 to the sump, 1 to waste. The valves will be operated by the PLC. When it's water change time I will have the waste valve open and the sump valve close, the return pump will run until it trips a low level float and that will kill the pump. Then the rest of the water over the level of the overflow will drain to waste. I will have to check but I think this should give me at least 25 gallons. Using another timer in the PLC when a set amount of time goes by to clear the waste water the valves will swap back closing off the waste and opening the sump. Then a small pump in the new water will come on. After it runs for a predetermined time, and the low level float switch is back off then the return pump can kick back on. I will probably have a timer set for the small pump as well as using the same float switch I will be using for the top offs in the sump as a backup. If anyone sees any problems with this let me know. As of now I think I have everything I need except for 1 valve and some float switches then the plumbing things.

 

[ccCapt]

Instead of using a timer, I would use a flow meter. I think it would be much safer to actually monitor the amount of water going thru the valve instead of going off a timer. Many things can slow down the flow, such as algae, debris, snails, etc. Even build up inside the pump can slow it down. You may be able to pump 5 gals in 2 mins 1 day and the next day it can be down to 2 gals in 2 mins. IMO, you would be better off monitoring the actual flow instead of hoping the amount of water pumped in the time you set doesn't change.

 

[jherrin215]

The only thing that i'm depinding solely on a timer will be leaving the valve open from the waste flow. It's won't be exact, i just wanna give it time to empty the hose. The rest will be using timers with float switches to monitor levels. Also the only place that I will need to monitor how much water is moving is old water out and new water in, which means the only pump involved will be in my new saltwater.

 

[land locked]

I want to reiterate what Kurt said. I vacume the sand during my changes so I am not sure you want to skip that chore. Great idea though! I am all about automation.

 

[jherrin215]

Do you just vacuum off the very top of the sand or do you do like in a freshwater tank and actually vacuum down in the sand??

 

[meegosh]

They usually just swirl the vacuum above the sand, the sand would get sucked up into the vacuum other wise. I've heard of some people putting some filter floss in the end of it to brush the sand also.

 

[jherrin215]

I was wondering because I have never had any suck vacuuming the sand bed. It always sucks up into the tube and won't fall out. I figured it would be best to just leave it alone. I can see the rocks though.