I do weekly water changes to keep nutrients low should I stop?

[Kodski]

Here is 345 citations from studies done world wide, including Marubini and Davies 1996 which is considered the best study on nitrate enrichment

https://www.semanticscholar.org/pap...vies/51065d2752eda4c079875e6d6da936dcb57048d2
I agree with a lot of you points, just pointing out elevated no3 has an impact on corals. It may or may not affect reef tank success but proof is clear.

Love anytime someone can share scientific research.

I would like to clarify though, my point wasn’t that elevated nitrates have no impact on corals. Of course high nitrates can be harmful to corals. I was saying that there’s no scientific proof that raising nitrate levels (within accepted ranges) affect coral growth rates or color.

 

[Randy Holmes-Farley Verified Community Expert]

However, “Marubini and Davies” is really all the proof needed, imo, as it is used in nearly all my books about nitrate enrichment effects on corals.

I do not think this complex field is well represented by promoting one old study. A review of dozens of more recent studies (last link below) shows a different result, and the fact that the situation is a lot more complex than "high nitrate reduces calcification".

I suspect that a lot of the issue with elevated nitrate studies is not having enough phosphate. That is borne out in these papers. Good reason to keep both at appropriate levels. :)

https://www.nature.com/articles/s41598-025-15683-5
Figure 3 b in above paper from 2025 shows that stylophora pistallata does not show decreased calcification at nitrate levels where your preferred paper does. In fact, the levels rise, though just a tiny bit.

This second paper shows the complexity of the discussion of seawater vs reef tanks levels, and suggests why nitrate may be more of a problem in the ocean than in a reef tank thaht has adequate (IMO) phosphate:

https://www.sciencedirect.com/science/article/abs/pii/S0048969722070449?via=ihub
"A deficiency of dissolved inorganic nutrients (DINut), especially phosphorus, in reef waters has potentially broad ecological effects on coral reefs. "
"These results suggest that under nitrate enrichment, corals were unable to increase their ability to rely on DOP and replenish their cellular P content."

https://link.springer.com/article/10.1007/s00338-025-02631-y
"Our findings highlight the remarkable tolerance of M. hispida to nitrate enrichment, possibly an adaptation driven by the nutritional profile of Southwestern Atlantic Ocean. "

This one may be the most interesting to us, since it surveyed lots of different studies and attempted to explain the differences in effects of elevated nutrients:

https://link.springer.com/article/10.1007/s00338-022-02223-0
Figure 1 shows the results from 25 studies of 92 different comparisons. If we look at HNHP (high nitrate high phosphate) we see across all species as well as in acropora specifically, we see more studies showing no effect or an increase in calcification as show a decrease.

 

[CHSUB]

I do not think this complex field is well represented by promoting one old study

I would agree it is a very complexed subject with no real “right or wrong” especially when studying the adaptability of living animals. However, I prefer Borneman’s explanation for nitrogen enhancement, “…. the potential for misunderstanding this information is substantial. When the zooxanthellae have an enriched nitrogen environment, they do not translocate as much to the animal, and instead use it for their own growth”

On a simpler note, my personal opinion is that an aquarium with high residual nutrients, not from dosing, in most cases is just not clean enough with increased bacterial activity; which may potentially lead to conditions like rtn, stn, BJD…etc

 

[hardcorn77]

I kinda had the same problem with ALF reef and high calcium. I lowered my dose but continued dosing until I saw my calcium reach below 450. I use tropic Marin pro so the Alk is a little low for me so I add some soda ash to my new water to raise it to 9. I also do a 10%water change weekly and totally believe in it. Your nutrients look good to me and I would just slowly bring down that calcium with less dosing and your regular water changes.

 

[LafondReef]

Well, I have found that it was tough to try and adjust for anything once a week and adding a broad array of things in bigger doses often spells disaster. Water changes I find key to lowering my phosphate but to many depleted my tank (to clean) everything needs to be done in slower stages anything drastic often creates more chaos. You start chasing numbers. Try lowering the amount you change and only add what's needed as needed. Try adding for alk smaller twice a week or even invest in a small doser for 24 hour level adjustment. I think you will find your calcium consumption might also change. This is also based on what your tank has for corals that are consuming calcium. I feed my fish heavy and have high levels of phosphate. So for me waterchanges are key.. but my LPS struggles many in this hobby forget the whole picture and get caught up in the Chase of one or two items.