Backyard Aquaponics
A place to discuss aquaponics

water in fish tank, how often should water changes be performed? thanks

How many gallons? How many and what types of fish? Are you running any filters?

Rule of thumb is no more than 10% weekly

would the aquaponic use up most of the nitrate and other nutrients? or weekly WC is still necessary on top of the intake by the plants? Thanks

a weekly water change is good in a small system to prevent rapid ammonia and hardness buildup. Not to be confused with "adding" water to replace evaporation loss. Change no more than 10% and add a dose of aquarium salt and pond conidtioner at every change.

Slow the boat down. Is this an ap set up your talking about or a simple fish tank? lol

An established and properly balanced AP system only requires top-offs. In fact, when I was establishing a 50gal fish tank recently (and was doing 50% daily changes to get ahead of the nitrite spike), I used a lot of the ammonia-flavored water to top off my established 125gal AP system. I knew those filters could handle the relatively small ammonia spike quickly.

true. I have now often changed out my over stocked indoor aquarium water with high nitrates into my outdoor AP tank as "top up" water.............so that would be like a negative change out

Over time, a lack of water changes will see the water chemsitry change, most notably the Ph will become acidic. Not a big deal really, but your buffer Kh starts to suffer, and ammonia spikes become more common. However I read that the ammonia spikes become less lethal. I've never suffered a fish loss due to poor water quality, but I do try and change out at least 10% of the water every few weeks. In a smaller system such as my 55 gallon aquarioum, it is weekly.

I'm lazy on water changes.
I top up my aquarium water when the noise from the power heads gets too loud. I change about 10-20% of my water approximately when I get around to it (6 months or so).

I have a healthy amount of gravel in my undergravel filter, and run it with 3 power heads (one of which is feeding my pilot AP system).

I can stir up the muck, (usually when I hit it with a gravel vac to clean up the aquarium and do the water change) and it will be clear in just an hour or two (the advantage to high water turnover).

Hi,

I've operated a small system (600 litres) and my 'water changes' take the form of open loop coco peat growing systems.......and, as Michael said, they've tended to be a maximum of 10% per week (plus a little bit more for evaporation and transpiration by plants). Since the 'water changes' go onto my open loop growing systems that water is never wasted.

As the weather cools, I'm finding that I'm using less water on such changes which suggests that it's time to start planting more coco-peat trays.

Gary

I only do top offs, never change any out, so thats bad? In an AP system?

I don't think so John. I think you only need to do changes if you have an a problem with the system or when it is first new (dealing with ammonia spikes or similar).

It's not bad in my eyes, John. It really depends on how your fish vs beds vs CaCO3 are balanced. If you are not having problems keeping your nitrate down and your pH up, then all is good. I think the key is to be aware of your water chemistry.

I agree that balance can be maintained without any water changes. Addition of CaCO3 deals witht he PH drift issue.

well seeing as how I never took the time to study water chemistry beyond the home aquarium, I just do my small water changes to keep the AP god's appeased. Should I sacrafice oyster shells too?