# Water Change



## Mark82 (5 Apr 2017)

Hi all,

So I’m hoping someone can provide me some more insight into why we need to do a weekly water change.

I know everyone says you need to do between 25 to 50% water change weekly, but for me I want to know why, I am trying to understand why we need to do this. 

Before I go any further I should say, I currently have a red sea 350l, setup for freshwater/planted that’s been running for about a about a year. It is not massively stocked with fish or plants and I dose EI with Mac and Min every other day for 2 weeks and then do a 50% water change every other week.

Lighting are on for about 7hrs each day and I have a CO2 and Ph meter setup to maintain a 0.8/1 drop 24/7

So back to the question, why do water changes, I can think of several reasons as follows:


1) Reduce Ammonia, Nitrite and Nitrate levels.
My Ammonia is 0, Nitrite is 0 and Nitrate gets to about 60 after 2 weeks. (I currently do bi-weekly water changes)

I have been looking to introduce a Nitrate filter/reactor that should keep the Nitrate levels under control (i.e. 20ppm). If it works Nitrate will no longer be an issue.


2) Remove organic waste
I have sand so I just do a quick hover over during the water change, but I don’t see a lot of waste as the flow keeps most suspended and is taken up by the filter. The little that remains accumulates around the base of the plants so my view is it will just add nutrition for the plants. 


3) Water clarity,
Not had an issue with this as yet, run 2 filter bags that polish the water nicely. (Would still change the filter bags weekly)


4) Replenish other trace elements and minerals
What other elements minerals would need to be replenished?

Have I missed something, or if I am able to keep my A,N,N under control, I could in theory go to monthly water changes?

Don’t take this the wrong way I’m not looking to just stop doing water changes, but am looking at setup a Nitrate reactor. IF it works, then I might look to drop the water changes to every 3 maybe 4 week intervals. (This would also help when I am away on holiday and with work)


Many thanks all
P.S. Sorry for the long post but I’ve tries to predict and answer the basic question before they get asked.


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## Planted Bows (5 Apr 2017)

You've basically covered it  its more for the fact of cleanliness to be honest so the water doesn't get to stagnant if you catch my drift. If you look at it this way, in most cases there's always a water inlet and out let which means fresh water trickles in and out etc. Which in turn kinda makes the 25% to 50% water change happen weekly.

Sent from my D6603 using Tapatalk


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