100% Monthly H20 Changes?!?!

J

JRechcygl

New member
I've always been a fan of heavy H2O changes, don't get me wrong not infrequent oops I'd better do a big water change, just decent sized changes. So I was thinking, I know Randy Holmes Farley says he does 1% daily, I was thinking I'd do 3% everyday that would be 100% monthly. I've read so much where biologists or so called marine gurus say well balanced tanks don't need regular water changes, I thought I might add that makes me cringe, but my thought is this, the ocean constantly renews the reefs with new water and expelling the wastes to the lagoons and so forth to reduce the nutrient levels. If I did changes with such frequency but still changed out all the water monthly, I bet I could theoretically eliminate all supplementation of elements Ca and Mg included. Also the way I look at it pulling out like 7-8 gallons out at a time and refilling it would take me maybe 15 mins or so tops.

Any thoughts folks good or bad?
 
It wouldn't harm anything and you'd probably have pretty awesome parameters (assuming you're using a balanced salt), but that's a lot of salt, water, time and money. I'm a big fan of making things as easy as possible as a rule, because the easier things are the more likely you are to actually do them and stick with it. I don't think 3% is really necessary, 1% a day (automated perhaps?) should be great assuming you have otherwise good filtration and husbandry (not too high a bioload, skimmer, live rock, etc.)
 
That is my goal is stablity and ease. I also want to change it all out. 1% a day is still 30% or so a month, I already do more than that either 10% a week or if I'm way too busy I'll scramble and do 25% bi weekly. I do not plan to overstock as I'm not going to add anything else to the tank. Well I'll say this, the tank is a 180 and I'm in the process of adding a 25gal sump,25 gal fuge and a 15gal maybe larger if possible frag tank. The bioload is a purple tang,orange shoulder, a blue angel which will leave, a flame, I will most likely bring in 2 true percs from my other tank as well as 2 scooters from my other tank, a six line wrasse and 8 green chromis. So its not a very heavy load-until the orange shoulder is huge!!! As far as salt,$, time and water- salt=money and I'm hoping I can convince one of my reps to sponsor the salt, water is free where I live-RO cartrides though are not, time should be about the same so in my eyes it will be equal to what I do now. The way I'm hoping it will work, once I upgrade the lights I plan to have a heavy SPS load, using lots of Ca and other elements, the frequent addtions will keep the system stable w/o a Ca reactor, dosing or even kalk. That is my hypothesis, the goal now is to actually see how it will pan out. The main issue would be to ACTUALLY STICK WITH IT!
 
30 3% water changes only comes out to about 60% change monthly, not 100%. You're already doing about 35-45% a month. Especially in a tank with high demand for cal and alk I don't think you're going to come anywhere close to meeting the demand in this way. It's also about the most expensive and time consuming (unless you automate it) method of trying to do that. At 8 gallons a day, that's about 2 buckets of salt per month!

If you're really set on trying this, my suggestion would be to double the size of the daily changes so you can get about 85% monthly. Obviously, if you're paying for salt that would be very pricey.
 
Yeah 30 3% changes will only get you to reduce the parameters that you want by 59.899%.. like GB said 60%. Might as well do 1 50% water change a month than 30 3% changes.
 
I'm not understanding, how does a 3% everyday equal less than 60%, when I add the sump, 'fuge and the frag tank I'll do larger amounts, and yes I know it will be a good amount of salt, but look at it this way, I use Coralife which has an absurd amount fo Ca and it'll work for the Ca issue. Plus salt aside, its trying something new, how else did this hobby come so far, 30 yrs ago no one would believe you could keep inverts, look at the way SPS keeping has come along!
 
It comes out to less than 60% because each time you do a water change, the new water gets mixed with the old water. Each time you do a water change after that, 3% of the water you remove is water you've already changed. If you express that mathematically, it's 1-[(1-WC%)^n], where WC% is the percent you're changing per WC expressed as a decimal and n is the number of changes you'll be doing.

This really isn't anything new though. People have been doing WCs of all sorts of sizes and frequency from 100% to 0%, from continuously to never, using NSW and ASW. I say this is unlikely to meet your demands based on my personal experience. In a modestly stocked 5 gal where I did 100% WCs monthly, I still couldn't meet calcium demand with hard corals.
 
Unless you do it all at once you can never get 100%.

You can get close by doing larger daily WCs, but the function is asymptotic, so you never quite get there. As you increase the percent changed, the effect becomes less and less. For example, going from 1% to 3% daily changes will take you from about 30% to 60% over the course of the month while going from 11% a day to 13% a day will only take you from about 97% to about 98.5%

To get 99% in a month you would have to change about 14% daily
98% would take about 12% daily.
95% would take about 10% daily.
90% would take a little over 7% daily.
85% would take about 6% daily.
70% would take about 4% daily.

5% daily would get you about 78%.

If you wanted to, you could set up an optimization function to figure out how to maximize the monthly WC percentage and minimize salt use. Just guessing, I would say that's probably somewhere around 4 or 5% daily.
 
I show how to do such calculations here, including continuous water changes.

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

Might as well do 1 50% water change a month than 30 3% changes.

I don't agree. I think there are many reasons to do many small or very small changes, even if they are a little less efficient. Much less stress, easily automated, no need to heat or match salinity or even aerate the water, etc.

This graph sows the relative effect on nitrate levels of 7.5%, 15% and 30% changes monthly, either as one big change (the jumpy lines) or with continuous tiny changes (the smooth lines) the results are very similar.

Figure 13. An overlay of Figures 3 and 12 to allow comparison of the differences between nitrate depletion using daily and monthly water changes of the same amount changed.

Figure13sm.GIF
 
This is what i do

Granted neither contain SPS, and the FOWLR is not demanding and use freshsea water and do not mix anything.

I have a 24g aquapod... change 2 gallons a day sometimes take one day off... the water i remove from the nano reef if stored into 35 gallon rubbermaid container with heater, pump, and carbon.

At the end of the week i do weekly 15 gallon changes to my FOWLR tank with the water i took from the nano reef tank. by far much better qality water than whats in there.

I would be getting 15 gallons a week for the 90gal FOWLR anyways(120gal system)... the nano reef water is still good quality with 0-1 nitrates and good parameters for the FOWLR tank so no wasting. Nano reef tank is 1.026sal, 0nits, 350+ppm calc, 12dkh, 8.3ph

the FOWLR tank essentialy has the same perameters except the calc level are a little lower ph is at 8.2 and Nitrates can range depending on the amount of feeding i do 20ppm nitrates.
Only use protein skimmer, carbon bags, and 125lbs live rock for filtering.

Fresh seawater 15gala week is per/week $5.25
Carbon think $25 a year= per/week $0.48
Phosphate media $40 a year= per/week $0.76
RO/DO topoff 5gal a week .85gal per/week $4.25

TOTAL COST A WEEK(including filter media) $10.74

I prolly could even cut the cost by 25% or so by getting my own RO/DI unit but would take a year before i start seeing any return for the cost of a good RO/DI unit only using 5 gallons a week. Also ;ooking into getting a phosban reactor to make that a llittle more effienct as it just sit under the overflow at the moment and i know Phosphate media works best water is being pushed through it, not just over it or sitting in a water colum for water to go around it.. could always ise polyfilter but again $$
 
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