Hauled my last bucket of saltwater! (Hopefully)

[Waterjockey]

Water changes for me consisted of syphoning rodi water into 5 gal buckets in the basement, hauling them up the stairs. I would then mix and heat the saltwater overnight with spare pumps and heaters. Next day I would syphon water from the tank to a mark on the side glass, then pump the new water into the sump from the buckets, clean and put everything away till next time.
A turn in health for me this year had made the task a physical burden that led to less and less frequent water changes, and a desire to automate the process more, so I decided to join the one percent a day club
My system is a about 100 liters, so for me that is only a liter a day. I have a controller, so I bought two 50ml/min dosing pumps, and a 120 liter bin on wheels. I ran the small lines to my sump, and programmed the apex to run the old water out pump for 20 min, then the new water in for 20 min once per day. To check the pump calibration, I set a 5 gallon tank beside my sump, and filled it with saltwater to about the same level as my sump to mimic real world piping frictional losses and head pressure (about 6 feet of vertical head between my saltwater storage container and the sump). After marking the level in the 5 gallon tank, and making a tight lid out of saran wrap (for evaporation), I set the awc to run every hour, so I could adjust the time of each pump run to maintain a steady level in the "calibration tank" , figuring once I removed and replaced exactly the same amount of water over 24 hours I would be good to go. I am almost there....on my (hopefully) final calibration run.
What really surprised me was the amount of "slippage" in the peristaltic pumps. The new water in pump has to run approx double the time the old water out pump does, to move the same volume. The "new water in" pump has to lift the water about 3 feet on the suction side, and then pump it up about another six feet to reach the sump. The "old water out" pump has, obviously about 6 feet of positive head on the suction side, and about a foot or two of downward pumping on the discharge. (Kinda like a controlled syphon I guess). Given the semi-positive displacement nature of peristaltic pumps I was very surprised to see this much difference in timing between the two.

On that note, water changes for me from here on out will consist of flipping a switch and turning a valve to fill my saltwater reservoir, adding salt and mixing via pump on a timer about once every 3 months now...I'm pumped!! (Pun intended)

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[JOKER]

Try getting the suction at the same height on both pumps and they will be almost dead on. The lift height really makes a difference. I am running a stenner and it is very noticeable at different heights.

 

[Waterjockey]

Try getting the suction at the same height on both pumps and they will be almost dead on. The lift height really makes a difference. I am running a stenner and it is very noticeable at different heights.

I can't do that, as the saltwater storage is in the basement, and the tank is on the main floor, by necessity one has to draw from basement level, the other from main floor level.
This is the main reason I didn't go with a duel head Stenner or similar set up, and two separate pumps, I was concerned about how much the different head heights would make.
I didn't expect it to be that much though. I used the brs pumps, which are only two rollers...I higher quality and more rollers pumps might not be as big a difference.
I'm also wondering now if there might be a bit of syphon passing the pumps.
Not that I have them equalized at once per hour, I'm going to let it run as it would in "real life" (once every 24 hours), into the test tank, for a few days to see if the level in the test tank changes due to syphoning, before I move it onto my DT. If it does, I may have to change it to an hourly system, instead of daily one

 

[mcarroll]

I'm also surprised....maybe return the BRS pumps and order some variable speed pumps with 3+ rollers instead?

 

[Brew12]

I can't do that, as the saltwater storage is in the basement, and the tank is on the main floor, by necessity one has to draw from basement level, the other from main floor level.
This is the main reason I didn't go with a duel head Stenner or similar set up, and two separate pumps, I was concerned about how much the different head heights would make.
I didn't expect it to be that much though. I used the brs pumps, which are only two rollers...I higher quality and more rollers pumps might not be as big a difference.
I'm also wondering now if there might be a bit of syphon passing the pumps.
Not that I have them equalized at once per hour, I'm going to let it run as it would in "real life" (once every 24 hours), into the test tank, for a few days to see if the level in the test tank changes due to syphoning, before I move it onto my DT. If it does, I may have to change it to an hourly system, instead of daily one

I love it! People like you make me wish I had a basement!

 

[ebushrow]

These dosing pumps work from a mechanical mechanism.....they will pump exactly the same...they are roller pumps, you cannot have a difference with flow unless you set one at a higher rate than the other....just make sure both are completely primed and let them go....

 

[Brew12]

These dosing pumps work from a mechanical mechanism.....they will pump exactly the same...they are roller pumps, you cannot have a difference with flow unless you set one at a higher rate than the other....just make sure both are completely primed and let them go....

I think his concern is that if the roller isn't tight against the tubing the entire time it could possibly create a siphon flow due to the large difference in height.

 

[Waterjockey]

I'm also surprised....maybe return the BRS pumps and order some variable speed pumps with 3+ rollers instead?

Heh. I think I found my issue. 2:00 am programming
For those with Apex systems, I had forgot to add the first and second "off" times together in the osc statement for the new water in. Which means instead of running 20 min each hour as intended, it would run 20 min, then be off for 70 min, run 20, etc. One of those Homer Simpson "Doah!!" moments lol.

Top of the hour I will try an initial calibration run with the fixed osc statement.

The brs pumps clearly don't have anywhere near the slippage I attributed to them. I'll post an update after the calibration run

 

[Waterjockey]

These dosing pumps work from a mechanical mechanism.....they will pump exactly the same...they are roller pumps, you cannot have a difference with flow unless you set one at a higher rate than the other....just make sure both are completely primed and let them go....

Agreed, thought peristalic pumps are really only pseudo positive displacement, the all exhibit some slippage..they will never pump *exactly* the same....Close enough for most things though

 

[ebushrow]

Agreed, thought peristalic pumps are really only pseudo positive displacement, the all exhibit some slippage..they will never pump *exactly* the same....Close enough for most things though

The slippage should be minimal as they are new...as the tubing within the pump gets used and ages, there will be more slippage, however, they should wear in the same manner and should stay fairly consistent.

 

[mcarroll]

Heh. I think I found my issue. 2:00 am programming

Good news! (And another case in point why I don't dig the added complexity of the Apex system vs some others.)

Close enough for most things though

And right....from the specs I've seen on the pumps that have specs provided, it's usually very close. Hopefully this will be your experience going forward! (Keep us posted!)

 

[gus6464]

My dual head stenner does not deviate from the heads if they are both primed correctly. Make sure the tubing does not slip on the head and there shouldn't be a variation even if the head heights are different. I have left my masterflex on my ca reactor off for a week primed and when I turned it on again it didn't require any more priming. If you have slippage then the tubing is old or there an issue with the pump head.

 

[Ralph]

Thanks for this guys. I want my system to do this. I have a basement sump system and can eventaially have mine dump waste water right into a utility sink.

 

[Waterjockey]

Thanks for this guys. I want my system to do this. I have a basement sump system and can eventaially have mine dump waste water right into a utility sink.

Perfect . Same here.
If you don't have a controller, a dual pump setup like stenner, masterflex, etc, or litermeter make for the ideal set up imho.
If you have a controller, or accurate digital timers, you can use individual pumps for new and old water if you want.
From what I've read of others experiences, if you are going to have "new" salt water sitting in storage for any length of time (weeks, months) pick a salt without organics in it (I. e. Instant Ocean over Reef Crystals for example).
Perhaps guys like @gus6464 and others who have practice running automatic water changes can chime in with tips/learnings gained from thier experience?
I liked the idea of individual pumps so that (a) if there was an issue with different volume rates, I could simply adjust the timing of one pump or the other to compensate, (b) I already had a controller, so it was relatively inexpensive to buy two 50ml/min pumps and be "in business" quickly, (c) I use the exact same pump on my kalk system, and ato system. If I had a failure with either one of those, I could simply pull one of the awc pumps to use while I waited for a new pump to arrive...."spares" that are doing something besides gathering dust on the shelf

 

[Brew12]

Have you taken into consideration that smaller daily water changes are less effective than larger changes weekly? It may not matter since some people don't do any water changes but I am curious.

 

[gus6464]

Have you taken into consideration that smaller daily water changes are less effective than larger changes weekly? It may not matter since some people don't do any water changes but I am curious.

That's a myth. They are super close and while a larger one is more efficient that math ends up being like if you do say a 20g large water change weekly you would need to do daily ones to equal 23-25g weekly.

 

[Brew12]

That's a myth. They are super close and while a larger one is more efficient that math ends up being like if you do say a 20g large water change weekly you would need to do daily ones to equal 23-25g weekly.

I'm not sure why you think it is a myth. Using your numbers it would reduce the effectiveness by 10%-20%. I do agree that it isn't a reason to not do daily water changes but if I were setting it up, I would try to take it into consideration.

 

[Waterjockey]

Have you taken into consideration that smaller daily water changes are less effective than larger changes weekly? It may not matter since some people don't do any water changes but I am curious.

I did wonder about that, but I based the decision to go that route for 2 reasons.
(1). I had done only 3, 20% water changes so far this year. Any method I employed had to be better than that
(2). I read some good threads with Randy Holmes-Farley about the subject where he included graphs showing the difference for things like nutrient export (not my goal here), between 1% a day and regular larger changes, and while 1% was less effective, it wasn't horrendously different. ...just slightly less "efficient".
I can live with that tradeoff for never hauling another bucket of water

 

[Brew12]

I did wonder about that, but I based the decision to go that route for 2 reasons.
(1). I had done only 3, 20% water changes so far this year. Any method I employed had to be better than that
(2). I read some good threads with Randy Holmes-Farley about the subject where he included graphs showing the difference for things like nutrient export (not my goal here), between 1% a day and regular larger changes, and while 1% was less effective, it wasn't horrendously different. ...just slightly less "efficient".
I can live with that tradeoff for never hauling another bucket of water

Couldn't agree more! Like I said, some people get away with never doing water changes. Sounds like you will actually be changing out more water with your new system! I just think it is something anyone reading this thread needs to be aware of.

 

[JOKER]

With my stenner I primed for 30 minutes before starting my test. Pump was brand new, and I had a considerable difference at 6' difference in suction height. I contacted the company I bought it from. They recommended replacing the brand new tubes in unit. Still the same difference on a 30 minute run after priming. I then got the suction heights within a foot of each other and they pumped the same. I am running the pump on highest setting so I wouldn't think there would be any slippage. Just my experience. I have also tested the brs pumps with same rate and gotten different throughput.