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??

 

[tfolke1]

I would think that should work. If you plumbed it in with a t connector and ball valves between the display and the aquarium sump, you could theoretically just divert the overflow into the sewer and run the same volume of replacement water directly into the sump. If you could arrange to do it at the same rate, you wouldn't even have a drop in water level.
I'm not sure what kind of impact the addtional connections would have on your water flow, and if you didn't get the rates the same you could overflow your Display.
You would still have to turn the valves manually and since they are in the basement you wouldn't be able to see the water level in your DT while you were doing it.

 

[mojo46825]

I think you can do this ok. You might need a few float switches to make sure that that you dont let the water in your sump get to low or get to much water in. Like they stated you might have trouble getting the water draining out to match the speed of it coming in. but if you put in a couple of float switches fora high and low level you could simply program those in to your PLC and have it turn on or off your valves and pumps. Shouldnt be too hard. I have been working on setting up and old SLC 500 to run everything on my 75 that I just setup. The only concern is the valves. What type of valve to plan on using for the saltwater. Just make sure you se something that wont leach metals into the water. I have a simple auto top off i did with a $5 float swith going to a relay to turn on and off valve for the topoff water coming from my RO unit. Good luck and let me know how it turns out.

 

[jherrin215]

On my city water into the RO I am usng a brass soleniod controlled valve. On the saltwater I have a couple of options in mind. I have the idea of pnuematically operated PVC schedule 80 ball valves or I would just manually have to open the valves but have proximity switches set up to verify that the correct valves are open before powering up or shutting off certain pumps. As far as overflowing the display tank, I have a built in corner overflow that would make it impossible to overflow the tank without overflowing the sump and with it in the basement I should be with it until I get everything set as it needs to be.

 

[wattsupdoc]

All you need are two float switches and 2 solenoid valves. IF you can install the new salt container above the sump. Just gravity feed with a solenoid valve at the sump. You could easily do this even without the plc. Just use a switch to activate the system opening the waste solenoid, an additional one to operate the float switches/new water. This would allow you to run the new water tank a tad bit longer than the waste water to catch up. Of course with the PLC, you can program it all in for a little more security.
I forget where I found them at, but was pointed to some solenoids considered to be reef safe. As long as the actuator, or any parts that come in contact with the water are plastic, rubber, stainless or better yet titanium your all OK. Actually the new water would be the only one you would have to worry about. As far as your tank goes anyways. Really anything that is rated for corrosive chemicals should be safe to use.

 

[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.

 

[wattsupdoc]

Actually, you can do this with the return pump running continuously. No need to shut it down, then restart it. Just Y off the drain, put a solenoid ONLY on the waste line, no need to stop flow to the sump. This would enable you to do various sizes of water changes if necessary. You could in fact do a 100% water change if you desired with this method. It's just a matter of controlling how much water is being removed vs. how much is being replaced. You could do a continuous WC if you wanted. Google Randy Holmes Farley, and water changes in aquaria for a real good read.
BTW, I dont believe I could get 25 gal. out of my 135 with the method you described. It would be just about the same amout that you can pull out in the sump without taking from the sump compartments themselves. Only the backwash and the return pump compartments would be all you could remove.

 

[jherrin215]

That's right, I wouldn't be removing anything from the water coming into the sump. I may have to look into something different. the only thing about not shutting off the overflow line is I don't have another pump near as strong as my return pump and I don't think i could use one to put water into my sump. It's an iwaki and it puts out some major water through the returns, can't remember the exact number right now, but it's a lot of volume.

 

[wattsupdoc]

My point is that you don't take ALL the water from the drain. Open a valve and allow some of the water to be removed, while some is still flowing into the sump. Through the system. You never interrupt the operation of the system this way. With the plc it would be easy to match your removal replacement rates. Use the float switches as "governors"(to match the flow rates), use time as a way of controlling how much water overall you change. You could do 1 gallon per day, or weekly, monthly etc. this way. You could also do a 100% change if you wanted.
So, Y off your drain reduce down to whatever your valve is(1/2" would be fine). Open and close that valve to dump. At the same time energize a pump that is providing new water. If the low level triggers, the SV closes. If the HL switch triggers, the pump or SV de-energises. Program a timing function into this to determine how much you change.
BTW, where did you get/what type of plc do you have? Is it difficult to program?

 

[mojo46825]

PLC's arent bad to program if you know what you are doing. and most importantly, you havet RSlogix software. depending onth plc you will need logixs 5 , 500, or 5000. I am hoping you are using a SLC,micro or compact logics. PLC 5 to old and big. and the 5000 well. A little much but hey, if you can get a good deal. lol. Add a couple of sercos cards and servo motors and you could have it do all kinds of things. Maybe add a small Fanuc or ABB robot to feed the fish. LOL ok maybe I went a bit out there. But I know Micro logixs are not all that expensive and if you have the software or access to it. Your options are far more advanced than the controllers on the market. I am going to setup the light timers a wave pulse and a auto top off with mine. The sky is the limit really.

 

[jherrin215]

I am using a mitsubishi FX for right now. I may upgrade if the need be later on but for this I think this will suffice. I love allen bradley and would like to have an allen bradley setup but I don't want to spend the extra $$ and I came across this one cheap!! And I am on track with you now doc!! This sounds goodm that could definitely work and like you said I could set it up to do it like a gallon every 3 hours or whatever I wanted, as long as I had salt water made up!!