Does anyone happen to know how aqadvisor calculates its WC schedule?

[RennjiDK]

Is there a certain setpoint of "X bioload generates 10ppm NO3/PO4 weekly" or something to that effect? I assume its calculations are for a sterile tank with no nutrient export?

[Fish Folk]

According to the webpage, the water change schedule is calculated based on the total bio load of the selected species.

There are many factors to consider. Water changes are helpful for elimination of excess nitrates, reconstituting buffer, rebalancing pH, diluting chemical buildup, etc.

Some aquarists have particularly unhelpful source water parameters, making water changes a challenge. For others, it is advisable to change 30% every two weeks on normal aquarium setups, and 30% once a week for more advanced scenarios -- e.g. delicate species, or certain breeding or fry grow-out tanks.

If you can get a Python hose (or similar) to attach to your home faucet to change water quickly, the process is not too much of a chore.

Now, there are methods of keeping fish that can rely on a different way to achieve balance. With a thick substrate bed, and a heavily planted aquarium, tanks can achieve a balance that requires only the occasional "topping off." This has been advocated by some well-known, experienced aquarists in recent years online.

I advise learning exactly what is going on in your aquarium as best as you can before going down the "no water changes" rabbit hole. 

[nabokovfan87]

My gut tells me it's tied to the overall max size of the fish.

[Pepere]

On 5/30/2023 at 2:24 AM, nabokovfan87 said:

My gut tells me it's tied to the overall max size of the fish.

My gut tells me it is more snake oil than science.  Too many variables not being considered.

Useful as a tabletop exercise when planning a tank stocking plan, but not to guide your water change schedule on an existing tank.

Now having said that I am a big fan of water changes, and perform significant water changes weekly, but not because of elevated nitrate levels….

Nitrate levels are going to be highly variable from tank to tank so that simply adding in variables such as species and number of fish, gallons of tank and filter you have can in no way determine nitrate levels at the end of the week.

Are the fish full grown or juvenile, is your tank densely planted or sparse, high light co2 injection or low light no co2.  Are you a chronic overfeeder?  All these factors will alter nitrate levels significantly.

at weeks end my Nitrate levels are right around 20 ppm with daily fertilization.

I water change as part of my weekly cleaning maintenance.  Every week I clean front and side glass and run my fingers through all of the plants to stir up and out settled solids and stir up dissolved organics amd then do a 50% water change to remove and dilute the same upon refill.  I then redose ferts to get back up to 20 ppm nitrate.   A single pump daily of Easy Green to my 29 gallon tanks in the morning replaces nitrates consumed by the plants the prior day.  My tanks stay between 10-20 ppm Nitrate all week long.

Edited May 30 by Pepere

[Ken Burke]

I don’t really know how they do it. But I kinda like the way Cory explained in one of his videos. The short of it is to test your water weekly. When the nitrates get too high, do a water change. Repeat. Over time, you learn how much and how often to do changes.  if your bio load is low and you have a heavily planted tank, the intervals can be rather long. If your bio load is high, like when I bred BNPs in a 20 gal,  water changes every couple days is a very real possibility. 
 

I think this is the video: