The theory of water changes and their affect on water parameters

reefing102

Who Am I Here?
Premium Member
So this is a genuine question. So we know that water replenishes elements in water. And we always reccomend to do water changes when something is out of whack. But my question is to what effect do the water changes help.

Say you have 100+nitrate and 3+ phosphate in an 10 gallon tank. In theory, doing a 50% water change should cut those numbers in half (provided you solve what’s causing those numbers). Is my thinking correct on this or would doing a 50% water change do only a 25% reduction in numbers? Thoughts?
 

mellotang

Premium Member
I do not know the specifics as to how much the water change will reduce the levels but that math sounds right

If your water quality was that poor though any help from water change will be short lived because of trapped organics

I see you said if you “solve what’s causing the numbers” so In that case I’ll agree with your math

I look at water changes more as preventative maintenance though

Kinda like brakes and oil changes of your vehicle
 

kharmaguru

Premium Member
Nutrient reduction is certainly applicable on small volumes like the proposed 10 gallon. On large systems using that as a control measure starts to get silly and expensive. Let's not forget on ANY size system this will likely be a highly destabilizing event to change that much water unless the hobbiest is super critical about matching calcium, alkalinity, magnesium, temperature, etc. A large water change is a last ditch effort when there is a large contaminant detected but I'm not sure what is harder on the corals - the contaminant or a new ocean.

I think water changes are much better at replacing trace elements and removing ditritus than trying to control the buildup of normal toxins which should be mitigated in other ways. Triton method has a highly reduced water change interval, and many hobbiests simply don't do water changes regardless of what maintenance scheme they choose to employ and still have success.
 

reefing102

Who Am I Here?
Premium Member
Lol so this is an actual tank and. A brand new tank (4 days old) at that. It was set up in an emergency as a local was breaking down his tank so I took in his BTAs (9 of them). I used existing live rock but new water and new sand. And they’ve been looking like crap since I got them.

So I had my wife test the water and those are the numbers using salifert test kits based on phone photos. I had her go get some phoszorb from the LFS as they don’t carry much salt water stuff. So I may run to another that actually carries some stuff.

I had her do a 4 gallon water change. I’m currently looking to get an AIO to get a proper nem tank going
 

JohnL

RC Staff
Staff member
Admin

Conducting Water Changes

Removal is simple enough if you carry out large, regular water exchange. Water changes are a sure shot, as they instantly and permanently remove the nitrate from the system.

Want to remove 20 percent of the nitrate in the water? Do a 20 percent water change; it's as straightforward as that.

Additionally, use of chemical filter media (such as the Deep Blue Professional nitrate reducer filter media pad) between water changes can provide very welcome relief in the event of an odd spike.
 

JohnL

RC Staff
Staff member
Admin

Information

I wish we could sell a natural product that could reduce nutrients as quickly as a water change, but biological processes take time. If you have to, or desire to bring your nitrates down quickly, water changes are the way to go. When doing your water changes, here are a few tips to remember:



Prepare the water used for your water change in advance. Ideally, the water used will come from an RO/DI or distilled water source, and mixed with a quality brand of salt. You should aerate the water and let it sit long enough until it matches the temperature and ph in your aquarium. Use a heater if necessary, ice can bring the temperature down if necessary.

Turn off all pumps and skimmers - Often this step will be forgotten until the water level gets too low, and the water change process is interrupted. A water change should not take too long, and the loss of current and filtration during this time should not be an issue.

Remove and clean any filter pads or micron socks that may be holding decaying food, and clean or replace them.

Allow any debris stirred up during this part to settle for a few seconds. Then begin siphoning the tank after the filters are in place again.

When siphoning the tank, you will be able to "vacuum up" more debris if you use a smaller tube rather than a larger one, because you get more time. We like to use 3/8'' diameter or smaller tubing for most tanks, and 1/4 for nanos. While siphoning, placing your finger near the entrance to the tube will help block out debris that can clog it, and serve as a means to stop it temporarily if you cover the hole. Should the tube get clogged anyway. smack it against the ground as if you were trying to whip an imaginary ant. That should dislodge it.

You will get a better result reducing nitrates if you do larger changes, even over a greater period of time than if you do smaller changes. Assuming a 5ppm nitrate accumulation over a course of a week, we get the following 6 month results:

(In this case, the tanks start off with 100ppm nitrates)

WeekTank A Weekly 10% Water Changes Tank 2 Bi Weekly 20% Water Changes1100 100295 85390.5 486.45 78582.81 679.52 72.4776.57 873.91 67.92971.52 1069.37 64.34

The results are much better at 40% weekly water changes, until corrected. From there, a bi-weekly schedule should keep it maintained, if 25% water changes are continued.

WeekTank A Weekly 10% Water Changes1100265344431.4523.84619.3

This chart will Help you determine how much water you should change in gallons each time to reduce your nitrates to 10ppm in 5 weekly water changes.

Aquarium Size in Gallons200ppm100ppm80ppm60ppm40ppm521.51.2510.7510432.521.52086543301297.564.5401612108650201512.5107.56024181512970282117.51410.580322420161290362722.51813.51004030252015110443327.52216.51204836302418130523932.52619.51405642352821150604537.53022.51606448403224170685142.53425.51807254453627190765747.53828.52008060504030



Happy Reefing! Hope this chart and info help.
 

mellotang

Premium Member
I’d start daily water changes till those anemones look better

Make sure you have good gas exchange in the tank

Thats a lot of anemones for a 10 gal

Is this a temporary holding?
 
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