The effectiveness and efficiency of low-rate drip systems

[CarpCharacin]

Something that I think needs to be discussed is the effectiveness and efficiency of drip systems in eliminating the need for manual water changes, the kind that just drips water in and has an overflow to remove the old water along with a filter, not the kind that completley replaces a filter. According to D Doc-Fish , if you drip 50 percent of the tank volume per day, it only removes 14 percent of metabolites, so you would have to drip around 130 percent of the tank volume per day to remove all waste products, which can be expensive, and is impractical. Why or why isn't this true? Please avoid using anecdotal evidence, if possible. Does anyone have any actual calculations about the rate of dilution needed to eliminate manual water changes?

 

[Yoimbrian]

The basic idea is with a normal water change you are taking out the toxins directly, with a drip system you are diluting the toxins before taking them out.

Say you have a 100 gallon aquarium. In a normal water change you take out 50 gallons of water, thus directly removing 50% of the toxins.

Then lets look at an extreme version of a drip system where you have a 100 gallon aquarium and you pour 50 gallons of water into it all at once, letting it overflow out. You still remove 50 gallons of water, but since you diluted the tank to 150 gallons before you did it you are only removing 33% of the toxins.

I don't think the 14% number is right at all though, but the math is certainly do-able to figure it out...its too early though and I have to go to work...

 

[Yoimbrian]

So here is a little smaller breakdown

If you do a "drip" by adding 1 gallon at a time and letting it overflow out of the 100 gallon aquarium.

So each time you are taking out a 1/101 fraction of the nitrate (or whatever toxin), such that if you pour 50x 1 gallon "drips" into your aquarium you'd remove 40% of the toxins, compared to 50% with a normal water change or 33% with an extreme "single drip" like my above math.

If you go smaller and smaller drips (down to, you know, an actual drip) the math will even out somewhere between 40% and 50% actual effectiveness of changing out 50% of the water. So I call B.S. on whoever said you only take out 14% of the toxins.

Here's math, starting at 50ppm nitrates

Drip ... nitrate
0 ... 50.000
1 ... 49.505
2 ... 49.015
3 ... 48.530
4 ... 48.049
5 ... 47.573
6 ... 47.102
7 ... 46.636
8 ... 46.174
9 ... 45.717
10 ... 45.264
11 ... 44.816
12 ... 44.372
13 ... 43.933
14 ... 43.498
15 ... 43.067
16 ... 42.641
17 ... 42.219
18 ... 41.801
19 ... 41.387
20 ... 40.977
21 ... 40.572
22 ... 40.170
23 ... 39.772
24 ... 39.378
25 ... 38.988
26 ... 38.602
27 ... 38.220
28 ... 37.842
29 ... 37.467
30 ... 37.096
31 ... 36.729
32 ... 36.365
33 ... 36.005
34 ... 35.649
35 ... 35.296
36 ... 34.946
37 ... 34.600
38 ... 34.258
39 ... 33.918
40 ... 33.583
41 ... 33.250
42 ... 32.921
43 ... 32.595
44 ... 32.272
45 ... 31.953
46 ... 31.636
47 ... 31.323
48 ... 31.013
49 ... 30.706
50 ... 30.402

 

[duanes]

I'm of the opinion that most drip systems are so slow (in most cases) that the new water becomes saturated with nitrate very quickly, so in reality doesn't amount to much of a water change.
My normal routine is 30%-40% every other day water changes, on 1000 gallons of tanks.
To equal that change a drip would need to be 300 to 400 gallons over 48 hours or a drip of at least 7+ gallons per hour.
But with normal water changes a lot of old water is removed all at once, so the old water (contains those nitrates and hormones )is flushed out, and a lot of new water flushed in, not slowly mixed and saturated with hormones and nitrates.

 

[Randys]

So are we thinking drip systems are way overrated?

 

[BIG-G]

So what if you didn’t drip the water in?
Let’s say you had 100 gallon tank and instead of dripping 50 gallons of water over a 24 hour period you dumped the 50 gallons in quickly over 20 minutes or so (how ever fast it takes to put 50 gallons back).
Would the resulting water change be effective?
I’m thinking it would be. Not as effective as directly taking out 50 and replacing ,but it would have to be better than a slow drip.

 

[monkeybike]

I supplement my drip with a well planted tank and the use of pothos and ivy to soak up nitrates

 

[Tanks of Steel]

BIG-G that sounds like the plan. This water change reservior (flush change method? can I start a phrase?) would need a float switch to close the refilling valve when the tank was full. It would need a heater that ran through that same float switch to heat it and it would need to be uncovered so that chlorination could disipate during a 24 hour heat-up period before a timed valve allowed the aquarium to flush (Yep, I'm using it. Aquariums are toilets afterall).

 

[RD.]

The following thread was posted by a local friend approx. 11 years ago. The pics are no longer showing, but the info is there for anyone that is interested on how Boydo had his 550 gallon drip set up. Even with a TON of large fish, he managed to keep his nitrates below 30 ppm.

I recall taking care of his tanks and fish while he was gone, he handed me 2 sheets of paper on what and how everything had to be checked each day. lol

https://www.monsterfishkeepers.com/...ana-comm-tank-filtration.125139/#post-1543358

This tank changed over the years, here's a vid of it at one point.

 

[RD.]

And his other display tank that was on a drip system.