Can you drop N03/P04 too fast?

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TCoach

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So question, can you drop your Nitrate and Phosphate too fast?

I just did a ~30% water change (~30 gallons) yesterday, and when I re-tested for Nitrate and Phosphate, they were 65ppm and 2.0ppm respectively (not a typo). The tank is ~17 years old with Fiji live rock, so I believe at least the high PO4 is probably due to leaching rocks, but can't prove that. But given the numbers, I need to drop PO4 by 99% and NO3 by ~90% from current numbers to get into recommended ranges. So, if I keep doing 30% changes 2-3 times a week, will dropping the chemistry that fast be a big negative? All the other numbers are in normal ranges.

I do have a refugium running with Chaeto doing some growth, but obviously, it's not making much of a dent right now. Also, I started a Bio Pellet reactor at the first of the month, but understand it could take 4-8 weeks to really kick in. Water flow in the sump is filter sock -> Chaeto -> skimmer -> bio pellets/Return pump. (Bio Pellets output is near skimmer input.

Only corals are the original shrooms, zoa's, frogspawn from when I adopted the tank and more recently I've added a frag of zoa's and an acan that seem to be doing good, but are obviously newer. The tank looks great visually, just the issue with nitrate and phosphate. I'm looking to keep the tank as a softie dominated tank with a few LPS, so that gives me a little wiggle room with them, but still, they seem really high right now.

Thanks for any advice.
 
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blasterman

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If you have live stock in the tank producing ammonia the water change will only have a temporary effect on nitrate. This is why I dont advise water changes for gross nutrient export. Nitrate will quickly go back up. You need to do a lot of water changes to keep nitrate beat down.

I've found biopellets more effective than chaeto once they ramp up can devour nitrate pretty fast.
 

Quietman

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The key here I read is "the tank looks good visually". That's not an easy feat for anyone. Those nutrient numbers obviously aren't that bad if everything looks good. Go very, very slow because yes, you can change things too fast - easily and with very significant consequences.

The reason why people chase those numbers is because they want a good looking tank...congratulations you have one. Make small adjustments if established tank.
 

lapin

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Like anything, including people they dont like change.
If you do it slowly the corals might not even notice.
I think water changes will help but it is not the total solution
You might try carbon dosing, GFO and your bio pellets along with water changes.
 

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I think the correct answer here is... "Sometimes..."

I've seen people drop NO3 and PO4 really fast without issue, but I've also seen it mess up a tank when done too much too fast.
 
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Timfish

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Reiterating the above "sometimes". All the biology in our ssytems messes with nitrogen and phosphorus and they doing it with both organic and inorganic so your numbers for total nitrogen and phosphorus might be very different. Not knowing these totals is a good reason to go slow IMO. What concerns me is your end goal of .02 PO4. That's low enough it can cause phospahte deficiency in corals and mess them up, I'd stay above .03 mg/l PO4 (keep in mind upwelling subjects corals to .2 mg/l) You might find these videos informative:

Forest Rohwer "Coral Reefs in the Microbial Seas"

Changing Seas - Mysterious Microbes

Nitrogen cycling in hte coral holobiont

BActeria and Sponges

Richard Ross What's up with phosphate"
 

Canyon08

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I wouldn’t say I’m an expert by any means. Definitely a newbie hear so take it fwiw but I do believe you can drop nutrients to fast. I have an lps dominant take with a few sps and decided my nutrients were to high for my sps (no3~40 po4~1) my lps looked great but sps not so much so I added gfo to get po4 down. I will say I don’t recommend adding as much as it says on the carton. Probably half that or less. At any rate my po4 dropped to 0 over night and I had a terrible cyano out brake. With that being said lowing nutrients with water changes should be a lot “safer” than what I did but like others have said if your tank and corals look happy. Don’t touch it. Don’t chase numbers. I don’t know how many times I’ve read experienced reefers say that. It’s sound advice. Don’t fix it if it ain’t broke! Good luck!
 

fachatga

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If your corals are doing good and you’re not changing what you want in the tank why does it matter what those numbers are? If the tank is doing fine making a drastic change solely to see numbers doesn’t make sense to me. The goal is coral growth and health so if you have that you’re fine.
 
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