chill105 Posted September 15, 2006 Share Posted September 15, 2006 When planning my nano-reef (you can see pics of the setup and progress of my tank in THIS THREAD), I knew I would need the ability to leave the tank pretty much on its own for relatively long periods of time (up to a month) without having to worry too much about it That meant reliable, precise, and consistent automatic water changes. (Auto top-off is obviously needed as well, but that's easy). Here's the diagram of how my system works: (UNCOMPRESSED VERSION HERE). The peristaltic pump is a reconditioned medical device. It works by "squeezing" silicon tubes wrapped around a rotating wheel. It moves very precise amounts of liquid (morphine drip, anyone?). It is unaffected by differences in water height ("head"), and can be programmed to move specific amounts. I have the tubes set up so that the pump is simultaneously (and slowly) moving water from the "clean" bin to the tank, and from the tank to the "dirty" bin. I guess I should call it an auto water exchanger. ...and here it is in action! Each bin is 20 quarts (5 gallons). Got 'em at wally world for a few bucks a piece. (The beer bottle in the "new" bin is to hold the intake line at the bottom. It's difficult to see, but the lines are running into the lids of the bins towards the back) pump closeup: ADVANTAGES -Continuous, reliable input of new saltwater into the tank -Consistency of water quality (no swings in temperature, any changes in specific gravity or pH would be very gradual) -Ability to optionally dose or buffer input water as desired -On my 8 gallon I could do >15% water changes (1.25 gallons/week) for 4 weeks by just pressing the "start" button! -It's super-quiet! DISADVANTAGES -Dilution of new saltwater. (Since the system is constantly adding and removing, the device will effectively be removing a little bit of the water that it added previously. This translates to needing to do slightly larger water changes to get the same effect as an "all-at-once" water change.) -Expensive (the pump, which is the main component of the system, ran me around $130 off ebay) FAILSAFES -Pump has battery backup. Can be set to either continue pumping or just maintain its setting and restart in the event of a power failure -Pump lines will not siphon (this is an advantage of a peristaltic pump) This is a very clean and simple system. There is only one disaster scenario I can think of: the silicon tubes used in the "pinching" section of the pump do NOT have an unlimited lifetime. They will eventually break, and it's tough to predict when this will happen (avg lifetime is ~6 months). IF the tubes broke, it would create a siphon in the line running from the tank down to the "dirty" bin. Hmmm... how could I prevent this from happening? I mounted the "out" line coming from the tank in a 15mL centrifuge tube. I put an air hole in the top and a tiny pinhole in the bottom. Under normal circumstances, the line draws water slowly enough that the water level inside the tube stays constant. However, in the event of a siphon, the line pulls water out faster than it can get back in through the pinhole, and the water level inside the tube drops until it breaks the siphon when air enters the line. This has been tested and it works great! I put a lot of time and thought into planning this system. So far it has changed over 2 gallons and is working flawlessly. Overall, I think it is a fairly elegant solution for a minimal-maintenance nano-reef. Your comments and critiques are much appreciated! (And don't forget to check out my tank thread HERE) Link to comment
reefhog Posted September 15, 2006 Share Posted September 15, 2006 Holy Macaroni !! This is a great idea !! Thanks for sharing. I will have to go try this now ... Link to comment
accord86 Posted September 15, 2006 Share Posted September 15, 2006 Cool idea. This is for the truely lazy IMO lol jk. I just got a 2-channel dosing pump for my ca/alk needs and it's great not adding supplements 2 times a day anymore! It might not be an efficient nutrient reducer though because when you change your water once a week, you let the nutrients accumulate, and reduce by replacing with NSW. This will have a different affect because you are changing very small amounts constantly instead of larger amounts every week. This is a very cool idea though and you really have a low maintainence tank. Link to comment
fewskillz Posted September 15, 2006 Share Posted September 15, 2006 Wow. I am thoroughly impressed. Very well thought out. I don't think it has the benefits of doing a weekly waterchange, but from what I've read, you don't either. Excellent insurance for vacations and other busy times when tank maintence could get neglected. A constant water exchange is better than no water change at all. Very clean DIY! Link to comment
chill105 Posted September 15, 2006 Author Share Posted September 15, 2006 Wow. I am thoroughly impressed. Very well thought out. I don't think it has the benefits of doing a weekly waterchange, but from what I've read, you don't either. Excellent insurance for vacations and other busy times when tank maintence could get neglected. A constant water exchange is better than no water change at all. Very clean DIY! Thanks for the compliments guys. Is anybody good at calculus? I'm trying to figure out exactly what kind of effect this has as opposed to a weekly all-at-once change. Back of the envelope estimate: >Let's assume I'm exchanging 1.25 gallons a week and that the tank volume (after rock, substrate, equipment, etc.) is 7 gallons. >In an all-at-once change, that would be almost an 18% water change. >Let's assume the system is taking out an equivalent percentage of the "new" water it previously pumped in. (This percentage climbs from 0% of total tank volume at the beginnig of the week to 18% at the end of the week). >Let's take the average percentage of the "new" water that's eventually getting pumped out over the course of the week to be 12% (this is weighted on the "more" rather than "less" side to be fair). >Multiply average percentage * volume pumped OUT: .12 * 1.25 = 0.15 gallons 1.25 gallons "new" water pumped in, minus 0.15 gallons of "new" water pumped out with the old water over the course of the week = 1.10 effective new gallons pumped in. 1.10 / 7 gallons = 0.157 So we're still talking about close to a 16% water change. Does this make sense? I realize there are a lot of other factors here... what else would make these continuous changes less effective? Link to comment
accord86 Posted September 15, 2006 Share Posted September 15, 2006 Check out this thread here. Maybe you won't get as confused as I just did LOL There's some good info about the topic though. Link to comment
chill105 Posted September 15, 2006 Author Share Posted September 15, 2006 Check out this thread here. Maybe you won't get as confused as I just did LOL There's some good info about the topic though. Haha, thanks for the link accord. That's a really great thread- very informative. Here are my conclusions: -Water changes are good -More frequent changes (or continuous, in my case) puts less stress on livestock, but may not be as effective in nutrient export -I need to exchange MORE water to have the same effect as an equivalent all-at-once change In any case, what I'm doing can't be bad. New water is good water. I guess time will tell how well this works... Link to comment
accord86 Posted September 15, 2006 Share Posted September 15, 2006 Yeah, the fact that it doesn't cause a shock to the system and added slowly is a huge plus. Keep us updated on how it works out. Link to comment
chill105 Posted September 15, 2006 Author Share Posted September 15, 2006 Yeah, the fact that it doesn't cause a shock to the system and added slowly is a huge plus. Keep us updated on how it works out. FYI, I just found a GREAT article on water changes (w/ data, graphs, etc..) Everyone should check this out: http://reefkeeping.com/issues/2005-10/rhf/index.php Here's the quote on continuous changes (the author has a similar setup to myself): "These changes are slightly less efficient than single batch water changes of the same total volume. A continuous water change of 30% exactly matches one batch 26% water change. As with very small batch water changes, these have the advantage of neither stressing the organisms (assuming the change is done reasonably slowly), nor altering the water level in the aquarium. The ease of doing such changes automatically also makes it far more likely that busy or lazy aquarists will actually do them." Link to comment
Mr. Fosi Posted September 15, 2006 Share Posted September 15, 2006 So you replace the tubes every six months? Link to comment
fewskillz Posted September 16, 2006 Share Posted September 16, 2006 I think you got as close to figuring it out with your math there as you're going to without getting really complicated and including flow rates and exponentials. Nicely done. Link to comment
nanofootball Posted October 4, 2006 Share Posted October 4, 2006 Will any peristaltic pump be able to run two lines like that? Also, do you think that running two lines would wear down the life of the pump? Link to comment
SaVeThEeELs Posted October 4, 2006 Share Posted October 4, 2006 i find myself looking at gagets everyday wondering why i didnt already think of that....... Link to comment
chill105 Posted October 5, 2006 Author Share Posted October 5, 2006 Will any peristaltic pump be able to run two lines like that? Also, do you think that running two lines would wear down the life of the pump? The "pump" itself is just a rotating wheel which squeezes the silicon tubes. Having one vs. two channels on it makes no difference to the pump itself, and should have no impact on the pump's lifetime. I'm not sure if you could run two channels on any 'ol peristaltic pump. The wheel on my pump is quite wide, which allows room for the two separate tubes. You may want to ask around and see if anyone's successfully set up 2-channels on a pump which was originally intended for only one. FYI, this system has been running FLAWLESSLY now for nearly 3 weeks. It makes a great drip acclimator too! Link to comment
SaVeThEeELs Posted October 5, 2006 Share Posted October 5, 2006 would it be cost effective to add another pump?? run them at diffrent times? would a bigger line help? my math skills are nill, but i understand 1+1=2 Link to comment
chill105 Posted October 10, 2006 Author Share Posted October 10, 2006 would it be cost effective to add another pump?? run them at diffrent times? would a bigger line help? my math skills are nill, but i understand 1+1=2 EeLsaver: I don't really know what you're getting at here. Are you looking to change more water during the week, or simply do the change in a shorter time period to be more effective? We established earlier that a slow, continuous water change is only slightly less effective than an all-at-once change. To compensate for the difference, you just need to change a little more water. There's also the added benefit of no drastic changes in water parameters (salinity, temp, etc..) I CAN hook a larger line up to the pump that allows for 300mL/hr, but then I can only have 1 line on the pump as oppposed to 2 (and thus would need an extra pump). To me, that's certainly not cost effective, but I guess that would vary on an individual basis. Link to comment
SaVeThEeELs Posted October 12, 2006 Share Posted October 12, 2006 basically i was just wondering if i could also benifit by getting one of these pumps, you answered ma question... bigger line does mean bigger water change but doesnt really mean better.....the never ending quest for stability.... how long have you been running this system so far?? Link to comment
chill105 Posted October 12, 2006 Author Share Posted October 12, 2006 how long have you been running this system so far?? The water changer has been running without any problems since my rock went in on September 14th, so close to a month now. Link to comment
kinetic Posted October 13, 2006 Share Posted October 13, 2006 looks cool! maybe you should keep your new water "stirred" with a tiny powerhead at all times? Link to comment
chill105 Posted October 13, 2006 Author Share Posted October 13, 2006 looks cool! maybe you should keep your new water "stirred" with a tiny powerhead at all times? Why would I need to do that? Link to comment
kinetic Posted October 13, 2006 Share Posted October 13, 2006 Why would I need to do that? so the water doesn't turn stale, salinity stays consistent. Link to comment
rev138 Posted January 7, 2007 Share Posted January 7, 2007 Wow. This is exactly the sort of device that gives me a nerd-boner Since the tubes only last 6 months or so: How much do replacement tubes cost, and are they easily obtainable? Link to comment
mybuickskill6979 Posted January 7, 2007 Share Posted January 7, 2007 okay i have a question. why not have two of these pumps run at seperate times, to be more sure that you are exporting nutrients?have one remove water. then when thats done have the other put the water back? if i where you along with adding a PH to the new water to keep the salt from precipitating out or the water getting stale i'd add a small heater to it as well. Link to comment
avalanche1201 Posted January 8, 2007 Share Posted January 8, 2007 been a while since we last heard from you...is the water change unit still working alright? any problems? and have you added anything to the NSW container to help the water stay fresh? Link to comment
Emrys Posted January 31, 2007 Share Posted January 31, 2007 I was going to start my own thread on this, but since it's directly related I may as well post here . Firstly, brilliant idea. The only problem I have with it is the pump (which cost about $130 you said), which I didn't feel like paying for. A bit of research online, and I bought this bad boy for $9.99 on ebay. A nice lab grade, 4 channel peristaltic pump that transfers up to 1300ml/h with the right tubing.. sweet . So, two water containers, tubing and the pump all only ran me about $60-$70. Because it can tranfer at such high rates I'm only going to leave it on during the time I'm at work and I'll get more than enough water changed out. Also, I bought tygon norprene tubing which apparently will last forever. At least thats what the internets tell me, and I'm certainly inclined to trust them. Hopefully this helps someone else if they're thinking of implementing this idea. Cheers Emrys Link to comment
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