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Offline Amstar

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Interesting water change method
« on: February 21, 2009, 08:22:37 »
saw this on the TOTM on reefcentral.

Water Changes
Unlike most systems that receive occasional, substantial water changes, I choose to do continuous water changes. This replenishes all of the important trace elements without shocking the system the way large water changes do. I change five and one-half gallons a day with the use of a Spectrum Litermeter III pump with two remote pumps. Five and one-half gallons of premixed saltwater are pumped into the sump of the system, spread out over a 24-hour period. One and one-half gallons are removed by the skimmer each day, and four gallons are pumped out of the tank. This happens every day. Instead of just pumping those four gallons of tank water into the drain, I have them routed into a separate aquarium that I maintain. From that second aquarium, four gallons are pumped out and go straight to the drain. Using the water removed from the main aquarium to feed the second aquarium lets me maintain perfect water quality in the second aquarium without using any filtration, since the water feeding it is being cleaned by all the filtration equipment in the main tank. However, unlike simply connecting the two systems in a traditional manner, this keeps the second system from being able to affect the main system (pests, water quality, etc.).


MechanicalEngineer

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Re: Interesting water change method
« Reply #1 on: February 21, 2009, 09:02:14 »
Scott and I were talking about this last night.  We were discussing the pros/cons of it.  I was considering this on the next tank to prevent what just happened to my tank (varying salts as well).  However, I think the cons outweigh the pros unless you're changing more than 10% (or some other arbitrary amount) per day.  If you regularly do a 10% water change weekly...doing a 10% water change constantly throughout a week wouldn't equal a 10% single water change (do the math.)  Yes, it's better to do several small water changes (which you can get to almost an infinite number through a continuous cycle), but your input/output would have to be greater. 

So, instead of a single 10% water change, to have the equivalent in a continuous water change, you may have to do a 20% water change (depends on size of tank and flow rate of the water in/out.) 

Now, let's add in risk.  Heaven forbid the pump dies somewhere...or the drain gets clogged...or whatever.  You either have a flood, a drained tank, or jacked up levels. 

Initially, it sounds good, but I don't think it's for me.  Thanks for bringing this topic up.  I think it's funny Scott (verper) and I were just talking about this yesterday.

Offline verper

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Re: Interesting water change method
« Reply #2 on: February 21, 2009, 11:06:57 »
That is funny Nikki. 

One of the things that would worry me about that guys setup is  "One and one-half gallons are removed by the skimmer each day".  Anyone's skimmer that accurate over a week or month?  I know mine changes by my feeding, how much the sand is stirred, etc.  He might deal with that by using floats or sensors to alter how much the litermeter adds.

I think another issue would be salinity.  You would still have to deal with evaporation.  My evaporation varies throughout the year.  If you're doing a 24 hr water change, when do you add the RO/DI for evaporation?  Maybe you could mix your saltwater at 33ppm to keep it at 35ppm in the tank in the summer, but it might change to 30ppm in the winter.  I think you would still have to fiddle with it a lot to keep your tank stable.

And like Nikki posted, you would need to add the 10% new salt water all at once to the tank and remove the 10% waste water from your sump all at the same time to get a true 10% water change.  Otherwise, you are  bound to be removing some of the new salt water.  That kinda defeats the idea of not shocking your system.  Or you have money to burn by flushing new salt water down the drain.

I would say continuous water changes could be done.  But at what cost?  Litermeter, sensors or floats, backups to these.

I was thinking more about this later in the evening for an easier way to change water.  If you could set up your sump to have an overflow directly to a drain and you pumped new saltwater directly into the display tank or return pump inlet in a fairly quick way (like a mag9.5, not a litermeter), the waste water would exit the overflow at the same time.  You would get most of your new water to stay in the system.  This could be set up to be a once a day water change with a timer on the pump.  The timer would be set to turn on just long enough so you would change x number of gallons a day.  You would draw out of a large container of newly mixed and cured salt water so it could last up to a week.  The only things I see being cons are that you need a access to a drain, there would still be issues with the evaporation water sensors having to be set at just the right hieght in relationship to the sump overflow, and if that overflow gets blocked your sump will overflow. 
« Last Edit: February 21, 2009, 11:09:53 by verper »

Offline cyberwollf

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Re: Interesting water change method
« Reply #3 on: February 21, 2009, 12:02:48 »
doing a 10% water change constantly throughout a week wouldn't equal a 10% single water change (do the math.)

Since most people won't :)  and i was curious, i broke out excel.

to illustrate the idea, say we have a tank filled with 100% dirty water

to make the math simple we will say its a 100 gallon system.

50 gallons at once would leave us with 50G dirty water and 50G clean water

It doesn't matter how quickly or spread out, multiple water changes adding up to 50 gallons is not as effective

5 gallon for 10 days is actually
day 0 100G dirty water 0G clean water
day 1 95G dirty water 5G clean water
day 2 90.25G dirty water 9.75G clean water
day 3 85.75G dirty water 14.2G clean water
day 4 81.5G dirty water 18.5G clean water
day 5 77.4G dirty water 22.6G clean water
day 6 73.5G dirty water 26.4G clean water
day 7 69.8G dirty water 30.1G clean water
day 8 66.3G dirty water 33.6G clean water
day 9 63G dirty water 37G clean water
day 10 59G dirty water 40G clean water

I was surprised, I thought it would have been worse.  The point being that by doing it in multiple changes, you are diluting the dirty water and removing some of your clean water on subsequent water changes too.

I do think depending on the system and nitrate production and trace mineral use it is ok to do it this way, just realize you are not being as efficient and wasting money on salt and water.
75G Mixed Reef w/ 30G sump/refuge

Electrical Engineers do it on impulse, with faster rise times, with more power, and less resistance at higher frequencies, without shorts, until it Hertz


Offline aquavista99

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Re: Interesting water change method
« Reply #4 on: February 21, 2009, 15:53:06 »
Since most people won't :)  and i was curious, i broke out excel.

to illustrate the idea, say we have a tank filled with 100% dirty water

to make the math simple we will say its a 100 gallon system.

50 gallons at once would leave us with 50G dirty water and 50G clean water

It doesn't matter how quickly or spread out, multiple water changes adding up to 50 gallons is not as effective

5 gallon for 10 days is actually
day 0 100G dirty water 0G clean water
day 1 95G dirty water 5G clean water
day 2 90.25G dirty water 9.75G clean water
day 3 85.75G dirty water 14.2G clean water
day 4 81.5G dirty water 18.5G clean water
day 5 77.4G dirty water 22.6G clean water
day 6 73.5G dirty water 26.4G clean water
day 7 69.8G dirty water 30.1G clean water
day 8 66.3G dirty water 33.6G clean water
day 9 63G dirty water 37G clean water
day 10 59G dirty water 40G clean water

I was surprised, I thought it would have been worse.  The point being that by doing it in multiple changes, you are diluting the dirty water and removing some of your clean water on subsequent water changes too.

I do think depending on the system and nitrate production and trace mineral use it is ok to do it this way, just realize you are not being as efficient and wasting money on salt and water.

Very nice analysis, cyberwollf!

MechanicalEngineer

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Re: Interesting water change method
« Reply #5 on: February 21, 2009, 16:21:24 »
Actually, we did the analysis too a while back, just didn't feel like digging up the file.  :)

Offline cyberwollf

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Re: Interesting water change method
« Reply #6 on: January 27, 2010, 21:54:22 »
 ADDED: Aww... the pictures were all resized and screwed up on Photobucket... the excel sheet is attached (only change values in the highlighted cells)...

So I was bored in a meeting today so I built a spreadsheet.  I figured this thread was as good as any of the other 5 water change threads to resurect.  I am now convinced that I do want to do tiny daily water changes in my new setup.  The really intresting thing about seeing the spreadsheet i built is that you normally only see the calculation out to about 10 waterchanges (the sheet has 1/2 years projection).  After a month or so (depending on build up, WC rate, etc) you actually reach a horizontail asymtope on the levels. I have a few cases shown below:

*note* The Weekly Water Change Rate (WWCR) is given to the spreadsheet and it divided by 7 to get the daily rate.  Also, The setup starts the daily water change on day1 but the first weekly water change is on day7

1A. Nitrate - Assumeing a 0.1 PPM per day buildup (someone with wetdry and no natural nitrate reduction method), 20% weekly waterchange, starting nirtrate level of 5 PPM


1B. Nitrate - Assumeing a 0.1 PPM per day buildup (someone with wetdry and no natural nitrate reduction method), 50% weekly waterchange, starting nirtrate level of 5 PPM


As you can see. It doesnt really matter if you change daily or weekly you are approximatly at the same level.  Changing weekly will remove more that is just accumulated over the course of the next week until the next water change.  You can also see that the maintained level is based on your WWCR

2A. Calcium - Assumeing Absorbsoin of 20PPM per day (SPS tank), 20% WWCR, starting at 400 PPM


2B. Calcium - Assumeing Absorbsoin of 20PPM per day (SPS tank), 50% WWCR, starting at 400 PPM


You can see that even a 50% water change weekly wont keep up your Calium levels with this load

3A. This is the case for any generic toxin or "chemical warfare" unleashed by coral, 75 Gallon Tank, PPMs are notional


3B. This is would be the same case except with an additional 75G sump.  The same livestock exisits in the tank so with double the water volume, they only produce half the PPM per day (they arent going to double their toxin output)  This shows that you can still remove the same VOLUME of water you did in 3A.  Notice the %WWCR is differnt but gallons is the same


So if you add a sump it looks like there is no need to double your WWCR just to meet some magic Percentage.  All the numbers were made up so dont say they are impossible  :laugh:  they just prove a concept.  

Of course I am not advocating changing less water or less often...Why would you listen to me Im just a guy that knows how to play with Excel, anyone see any major flaws in this theory?

« Last Edit: January 27, 2010, 21:59:02 by cyberwollf »
75G Mixed Reef w/ 30G sump/refuge

Electrical Engineers do it on impulse, with faster rise times, with more power, and less resistance at higher frequencies, without shorts, until it Hertz


Offline HUNGER

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Re: Interesting water change method
« Reply #7 on: January 27, 2010, 21:56:40 »
nice work wes
SIZE DOES MATTER

Offline rmstevensiii

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Re: Interesting water change method
« Reply #8 on: January 28, 2010, 16:36:25 »
Very nice!
Dayton - 45459

Offline Wall_Tank

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Re: Interesting water change method
« Reply #9 on: January 28, 2010, 21:40:01 »
Could have saved yourself some trouble on this

http://reefkeeping.com/issues/2005-10/rhf/index.php

Offline cyberwollf

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Re: Interesting water change method
« Reply #10 on: January 30, 2010, 11:07:53 »
Looks like he stole all his data from me  :laugh:
75G Mixed Reef w/ 30G sump/refuge

Electrical Engineers do it on impulse, with faster rise times, with more power, and less resistance at higher frequencies, without shorts, until it Hertz


Offline HUNGER

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Re: Interesting water change method
« Reply #11 on: January 30, 2010, 14:21:01 »
yes it does wes
SIZE DOES MATTER

 

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