I am in the final phase of a 70 gal reef build in my office, 30 gal sump. I am wanting to automate as much as possible and water changes are top of my list....My office has a full bath and my plan is to convert this to a wet room with an RO/DI and storage tanks. I have two thoughts...1)run 1/2 lines to/from the tank for bulk water changes using pumps, or 2)run 1/4 inch line to/from and do continuous water changes using dosing pumps....I've never done continuous but it does sound intriguing...Thoughts? TIA!
Bulk water change vs continuous?
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I did some research, below is an interesting post by Randy Holmes...I need to digest this overnight....
The link he provided in the OP is gone but the results from his view is that there is only a slight advantage to bulk water changes vs continuous....From my analysis thus far is that a continuous water change system/approach may be more expensive to set up (dosing pumps and automation), it will save me (personally) a lot of time and effort...
from Randy.....
"I do semi-continuous water changes with a dual head Reef Filler pump.
I discuss the mathematics behind continuous water changes here:
Size of Water Changes: A General Case
As shown in the previous section, a fixed number of small water changes is not as beneficial as the same fixed number of larger water changes. However, for an aquarist who wants to do water changes, the decision of how to change the water should not be driven by that analysis alone. The conclusion of such an analysis is different if one assumes that the aquarist has a fixed volume of water to change, and is just deciding how to accomplish it.
For example, with a 100-gallon tank and a goal of changing 30 gallons each month, one might consider changing 30 gallons once, 15 gallons twice, 10 gallons three times, 5 gallons six times or 1 gallon 30 times. In the extreme case, we can imagine changing an infinitesimally small amount of water an infinitely large number of times, eventually consuming the entire 30 gallons (I actually do this in my aquarium, as I'll explain).
Aquarists often think that many small changes are not as efficient as one big change since some of the water in all subsequent changes was already replaced by earlier changes. This is a correct assertion, but it is often overstressed. After changing 10% three times, only 10% of the first 10% change was changed the second time (1% of the total). So the difference is small. We can mathematically calculate the efficiency of such changes as follows. If we use our 30% example, then one 30% change removes 30% of the impurities, assuming an equal distribution of the impurity within the water. If we do six 5% changes, then the reduction in impurities = 1-(0.95)6 = 26.5%. So it is less efficient (six 5% changes exactly equal 26.5% changed in one batch), but it is not radically less efficient. Going smaller still, the difference is even smaller. Doing 30 one percent changes removes 1-(0.99)30 = 26.0% of the impurities.
The extreme case of infinitely small water changes done an infinitely large number of times is approximated by continuous water changes that add water at exactly the same rate it is being removed. The details of how to do this mechanically are described below. This case is a standard example in advanced math textbooks (differential equations, specifically). Assuming the aquarium is well-mixed as the water is changed, the remaining impurities are given by:
I = Ioe(-C/T)
where I is the amount of impurities present, Io is the amount present at time zero, e is the constant 2.71828, C is the amount changed, and T is the tanks total volume. So for 30 gallons changed this way in a 100-gallon tank, the remaining impurity is 0.74 times Io, or a reduction of 25.92%.
The table below compares these results for a 30% water change done via different numbers of smaller changes. Clearly, the single 30% change is a little better than the others (70% vs. 72-74% initial impurities remaining), but the difference is quite small, and the difference between the others in efficiency is trivial."
The link he provided in the OP is gone but the results from his view is that there is only a slight advantage to bulk water changes vs continuous....From my analysis thus far is that a continuous water change system/approach may be more expensive to set up (dosing pumps and automation), it will save me (personally) a lot of time and effort...
from Randy.....
"I do semi-continuous water changes with a dual head Reef Filler pump.
I discuss the mathematics behind continuous water changes here:
Size of Water Changes: A General Case
As shown in the previous section, a fixed number of small water changes is not as beneficial as the same fixed number of larger water changes. However, for an aquarist who wants to do water changes, the decision of how to change the water should not be driven by that analysis alone. The conclusion of such an analysis is different if one assumes that the aquarist has a fixed volume of water to change, and is just deciding how to accomplish it.
For example, with a 100-gallon tank and a goal of changing 30 gallons each month, one might consider changing 30 gallons once, 15 gallons twice, 10 gallons three times, 5 gallons six times or 1 gallon 30 times. In the extreme case, we can imagine changing an infinitesimally small amount of water an infinitely large number of times, eventually consuming the entire 30 gallons (I actually do this in my aquarium, as I'll explain).
Aquarists often think that many small changes are not as efficient as one big change since some of the water in all subsequent changes was already replaced by earlier changes. This is a correct assertion, but it is often overstressed. After changing 10% three times, only 10% of the first 10% change was changed the second time (1% of the total). So the difference is small. We can mathematically calculate the efficiency of such changes as follows. If we use our 30% example, then one 30% change removes 30% of the impurities, assuming an equal distribution of the impurity within the water. If we do six 5% changes, then the reduction in impurities = 1-(0.95)6 = 26.5%. So it is less efficient (six 5% changes exactly equal 26.5% changed in one batch), but it is not radically less efficient. Going smaller still, the difference is even smaller. Doing 30 one percent changes removes 1-(0.99)30 = 26.0% of the impurities.
The extreme case of infinitely small water changes done an infinitely large number of times is approximated by continuous water changes that add water at exactly the same rate it is being removed. The details of how to do this mechanically are described below. This case is a standard example in advanced math textbooks (differential equations, specifically). Assuming the aquarium is well-mixed as the water is changed, the remaining impurities are given by:
I = Ioe(-C/T)
where I is the amount of impurities present, Io is the amount present at time zero, e is the constant 2.71828, C is the amount changed, and T is the tanks total volume. So for 30 gallons changed this way in a 100-gallon tank, the remaining impurity is 0.74 times Io, or a reduction of 25.92%.
The table below compares these results for a 30% water change done via different numbers of smaller changes. Clearly, the single 30% change is a little better than the others (70% vs. 72-74% initial impurities remaining), but the difference is quite small, and the difference between the others in efficiency is trivial."
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Now this is what I am talking about - as an engineer i knew there was a reason i was doing all those small water changes. From the sound of it, even mathematics proves there isn't much of a difference. Plus its a lot easier.
Something I just figured out this morning, not sure why lol. I recently got a dual float switch and controller thru a company called Dayton. Got it free from work so I decided to see what i could do with it. I quickly realized that this was for pumping water out of a sump filling with water not pumping water in to a sump emptying with water (ie evaporation). However, being the enginerd that i am i flipped the float switch upside down and there you have it. An auto top off system. A good one at that. To test it out i simply removed the water line coming from my phosban reactors and dropped that line outside of the sump in a 5 gallon bucket and the test was on. Water level dropped and the switch kicked on and filled up my sump with ro/di water from another bucket with a small pump. Then it all of a sudden hit me, what if I replaced the ro/di tank with a tank full of saltwater to do a water change. All i would have to do is take out the phosban reactor water line and let the ato system do its thing. Ingenious. I was so proud of myself for figuring this out I had to post it.
But then a few minutes later i started to realize all those pics of peoples ATO systems with 2 tanks side by side; one for ro/di water and one for salt water were in fact probably doing the very same thing i thought i had just revolutionized for doing water changes. haha this made me laugh out loud, oh well, i still figured it out so good for me.
I guess what i am saying is if you set up something like this you can make as many small or big changes as you want with very little interaction from you. It would be really easy with the right valving and a few solenoid valves to automate this type of system.
Dale
Something I just figured out this morning, not sure why lol. I recently got a dual float switch and controller thru a company called Dayton. Got it free from work so I decided to see what i could do with it. I quickly realized that this was for pumping water out of a sump filling with water not pumping water in to a sump emptying with water (ie evaporation). However, being the enginerd that i am i flipped the float switch upside down and there you have it. An auto top off system. A good one at that. To test it out i simply removed the water line coming from my phosban reactors and dropped that line outside of the sump in a 5 gallon bucket and the test was on. Water level dropped and the switch kicked on and filled up my sump with ro/di water from another bucket with a small pump. Then it all of a sudden hit me, what if I replaced the ro/di tank with a tank full of saltwater to do a water change. All i would have to do is take out the phosban reactor water line and let the ato system do its thing. Ingenious. I was so proud of myself for figuring this out I had to post it.
But then a few minutes later i started to realize all those pics of peoples ATO systems with 2 tanks side by side; one for ro/di water and one for salt water were in fact probably doing the very same thing i thought i had just revolutionized for doing water changes. haha this made me laugh out loud, oh well, i still figured it out so good for me.
I guess what i am saying is if you set up something like this you can make as many small or big changes as you want with very little interaction from you. It would be really easy with the right valving and a few solenoid valves to automate this type of system.
Dale
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I didn't think renters insurance covered property damage, like 150 gallons of water all over everywhere!
sorry this post was for a different thread...lol
sorry this post was for a different thread...lol
Thx Ralph...I don't read all the posts, that is an interesting read...
I am leaning heavily towards automating with dosing pumps and doing daily water changes, perhaps 1-2 gallons per day. I can always do larger changes if my params need it...On my last build, a 22 gal AIO, I actually found that my softies suffered from water that was 'too clean'. I was doing 20% changes weekly...I started doing monthly and they did much better. I think stability has a lot to do with it as well and smaller changes are always better in the reef world.
I'm looking at 2 pumps at the moment, BRS has a 50ml/day pump and LiterMeter has a 100ml/day version...the BRS pump is cheaper and I can easily automate this with my Apex controller. I have a BRS 50ml already for ATO and they work well. I'm also thinking I could stabilize the salinity by having 2 ATO's (one fresh and one salt) and use a salinity probe to determine which one to use....that and a bunch of float valves and I should be good to go....
I am leaning heavily towards automating with dosing pumps and doing daily water changes, perhaps 1-2 gallons per day. I can always do larger changes if my params need it...On my last build, a 22 gal AIO, I actually found that my softies suffered from water that was 'too clean'. I was doing 20% changes weekly...I started doing monthly and they did much better. I think stability has a lot to do with it as well and smaller changes are always better in the reef world.
I'm looking at 2 pumps at the moment, BRS has a 50ml/day pump and LiterMeter has a 100ml/day version...the BRS pump is cheaper and I can easily automate this with my Apex controller. I have a BRS 50ml already for ATO and they work well. I'm also thinking I could stabilize the salinity by having 2 ATO's (one fresh and one salt) and use a salinity probe to determine which one to use....that and a bunch of float valves and I should be good to go....
Personally, I don't think an automatic water change setup as you described would be very good. Not that you have not thought it out. But for one, I don't believe the BRS pumps are meant for continuous duty. They are hobbyist grade only, and not meant to run continuously or for long periods of time. I would not trust their quality level for what you want to do, personally.
If I were setting up an automatic water changing system, I would purchase a much higher quality, lab grade peristaltic pump, like a Masterflex pump, that can accommodate multiple pump heads. Then you fit it out with two identical pump heads with identical tubing. Have one intake go from your tank to the sink or wherever you dump the water, and one intake go from your new saltwater reservoir to the tank. When the pump turns on, it automatically pulls and replaces water from the tank at the same rate.
Determine the amount you want to change daily, then program the volume on the pump and have it do it in a relatively short period of time, like a batch type change interval, done once daily, which removes the evaporation factor from the act of doing it continuously. Then you remove the need to deal with salinity probes, which I believe at our level in the hobby, are of pretty dubious quality. This allows you to just check the salinity as usual.
For your tank, you could do this in a 1/2 hour easily. These Masterflex pumps can move a lot of water. Here is the unit I have that feeds my calcium reactor. This one can actually accommodate up to 4 pump heads. There are always used units for sale on ebay.
If I were setting up an automatic water changing system, I would purchase a much higher quality, lab grade peristaltic pump, like a Masterflex pump, that can accommodate multiple pump heads. Then you fit it out with two identical pump heads with identical tubing. Have one intake go from your tank to the sink or wherever you dump the water, and one intake go from your new saltwater reservoir to the tank. When the pump turns on, it automatically pulls and replaces water from the tank at the same rate.
Determine the amount you want to change daily, then program the volume on the pump and have it do it in a relatively short period of time, like a batch type change interval, done once daily, which removes the evaporation factor from the act of doing it continuously. Then you remove the need to deal with salinity probes, which I believe at our level in the hobby, are of pretty dubious quality. This allows you to just check the salinity as usual.
For your tank, you could do this in a 1/2 hour easily. These Masterflex pumps can move a lot of water. Here is the unit I have that feeds my calcium reactor. This one can actually accommodate up to 4 pump heads. There are always used units for sale on ebay.
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Stenner pumps are high qaulity commercial duty pumps as well and are available with multiple heads.
Not trying to be a PIA, but 1) I'm a hobbyist so why not go for a 'hobbyist' quality pump? is there any data out there that would point to a mtbf rate that is unacceptable on the BRS pumps? if so that would be good to know. 2) for the price of one of those pumps new I could buy 21 BRS pumps and have money left over for a few dozen float switches....I like the idea of one spindle pushing and pulling water at the same rate but then there are other factors that can alter the flow, i.e. clogging of the 1/4 in line on one side and not the other....I think I would still prefer to rely on automation and water level sensors to determine the proper dosing periods.
I'll look into the Masterflex further, thanks for the tip Acroholic...
I'll look into the Masterflex further, thanks for the tip Acroholic...
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Weird idea that popped into my head.
A gravity fed drain built into someone's sump would surely make the auto water change MUCH easier.
Hook a float switch to a timer and dosing pump.
Have an ATO to regulate evap, so the water changes don't raise the salinity.
Once a day, instead of turning a pump on to pump the water out, have the timer turn on the float switch and the feed pump. The float switch would be at the bottom of the mixing barrel and cut power when the water level is too low.
If you have a drain in your sump at a certain level, you could never over fill the sump. Instead of taking water out and replacing with new, you would be diluting the old with the new and dumping some of each.
Just a quick though- I probably wouldn't do this, just because preparing an auto waterchange woul probably be almost the same amount of hassle of just doing the water change.
A gravity fed drain built into someone's sump would surely make the auto water change MUCH easier.
Hook a float switch to a timer and dosing pump.
Have an ATO to regulate evap, so the water changes don't raise the salinity.
Once a day, instead of turning a pump on to pump the water out, have the timer turn on the float switch and the feed pump. The float switch would be at the bottom of the mixing barrel and cut power when the water level is too low.
If you have a drain in your sump at a certain level, you could never over fill the sump. Instead of taking water out and replacing with new, you would be diluting the old with the new and dumping some of each.
Just a quick though- I probably wouldn't do this, just because preparing an auto waterchange woul probably be almost the same amount of hassle of just doing the water change.
I suggest you call BRS and ask them if their pumps are applicable for what you want to do. I'll bet $ they tell you they are not intended or recommended by them for that use. Dosing pumps are not made for continuous duty.
No problem if you want to use a hobbyist quality pump, but there is no truer saying in this hobby than "you get what you pay for," and with most reef tanks having thousands of dollars of corals and fish in them, a malfunction in a system like an auto water changer can have really negative consequenses for all your livestock.
Masterflex pumps can be purchased used with dual pump heads on ebay for $200-$300, pretty much the same cost that you will have in your own design using BRS dosing pumps and float switches. No one said the Masterflex (or Stenner) had to be new. The cost for two BRS dosing pumps is $160 or $200 by themselves, depending on which ones you buy.
Of course, do what you think is best, but a high quality peristalitc setup is nowhere as expensive as you are thinking it is.
greenclaws
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Interesting post about small vs large water changes. However, the article you reference doesn't take one important thing into account: during that theoretical one month period, waste is constantly being added to the water, and those calculations are only looking at reduction of a fixed static amount of waste.
Taking that into consideration, I think the advantage tips more in favor of larger less frequent changes, and the minimal difference between the two methods becomes more significant. Of course, this isn't considering the stability of various parameters that come with small frequent water changes. But the advantage of large vs. small water changes is dependent on the amount of waste a tank produces, which varies from tank to tank.
Taking that into consideration, I think the advantage tips more in favor of larger less frequent changes, and the minimal difference between the two methods becomes more significant. Of course, this isn't considering the stability of various parameters that come with small frequent water changes. But the advantage of large vs. small water changes is dependent on the amount of waste a tank produces, which varies from tank to tank.
I did contact BRS...and while they said their pump was not hobby grade (a marketing response imo) they did not recommend this pump for this approach. I am still intrigued with the notion of doing more frequent water changes...and automation is an absolute requirement for me....perhaps not continuous but perhaps daily or twice daily small changes. I've been researching the Stenner pumps and have contacted them regarding operations at the rates I have proposed and they are confident that the pumps they make will easily support daily operation and have double head pumps that can move up to 100 gallons per day....a 30 minute session will change 2 gallons, not bad...
Phase 1 complete....I ordered a Stenner 170 dual head adjustable pump and a pair of 40 gal storage tanks. The 40 gal tanks will allow me to swap about 2 gals per day and go 2-3 weeks between SW mixes. I've also ordered a new BRS ATO pump, I already have one of these pumps. This second pump will be for topping off SW should the salinity levels drop. Now the transformation from bathroom to fishroom begins....
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If u don't mind me asking where did U get those tanks and how much each?
Plastic-Mart...$120 each, after shipping cost.
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