Nitrates and Phosphates - Water Change %

[taki123]

Hi guys,

I have a 350L reef tank and am super high on nitrates and phosphates.

Here are my parameters:
Nitrates - 75+
Phosphates - 0.9
Alk - 15.2
Calcium - 520
Magnesium - 1230
Salinity - 1.026
pH - 8.3

I really need to reduce these numbers because I have a lot of algae and some of my coral aren’t so happy.

What % water change should I do and how frequently to avoid impacting my fish and coral negatively?

I’ve changed 15% each day for the last two days.

Should I keep doing 15% daily or what?

Any help would be appreciated!

 

[fishywishy]

you can keep doing that after changes but it’s just gonna keep going back up. You need to cut down on some fish or get better filtration.

 

[Lavey29]

Your alk is sky high too which will harm your fish before the elevated nutrients do the tank.

 

[Ben's Pico Reefing]

You can do as big of a water change as you want using same salt mix and close to same temp. However, as stated, you need to figure out the source and cause or you will be right back to this point. Either not enough maintenance, over feeding or something dead/leaching causing this

 

[taki123]

you can keep doing that after changes but it’s just gonna keep going back up. You need to cut down on some fish or get better filtration.

I’ve actually got an oversized skimmer, fleece filter and UV running to help. These number used to be much lower

 

[SaltyCrew4u]

Hi guys,

I have a 350L reef tank and am super high on nitrates and phosphates.

Here are my parameters:
Nitrates - 75+
Phosphates - 0.9
Alk - 15.2
Calcium - 520
Magnesium - 1230
Salinity - 1.026
pH - 8.3

I really need to reduce these numbers because I have a lot of algae and some of my coral aren’t so happy.

What % water change should I do and how frequently to avoid impacting my fish and coral negatively?

I’ve changed 15% each day for the last two days.

Should I keep doing 15% daily or what?

Any help would be appreciated!

First off, what are you feeding your fish and how much? Your Alk seems very high as well. Are you using RODI and mixing your own salt or purchasing from LFS. 350L/90 gallon. IMO I would do 40 gallons. I have done 50% water changes with zero negative results. You say .9 phos. Is that .90 or .09?

 

[SaltyCrew4u]

I’ve actually got an oversized skimmer, fleece filter and UV running to help. These number used to be large water c

A large water change is your best bet. But i think that's also raising your alk. UV isn't doing anything for what you listed above. How old is your tank? Sand and live rock?

 

[CHIEF_OF_THE_REEF]

how old and what test kit are you using?

 

[I never finish anythi]

Personally I'd start carbon dosing with the weekly 10% water changes.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, water changes are not the best way to deal with phosphate. Even a 100% change may end up only lowering the phosphate level slightly.

 

[SaltyCrew4u]

FWIW, water changes are not the best way to deal with phosphate. Even a 100% change may end up only lowering the phosphate level slightly.

ROWA Phos works well

 

[taki123]

Thanks for all the responses guys.

I am aware that my Alk and Calcium are also too high. Luckily my fish have shown no sign of being unwell so far.

Not sure what the source is for phosphates and nitrates. I am aware of why my alk and calcium are high which is due to me taking out a lot of GSP that was taking over my tank and keeping my dosing the same. So it overshot badly.

I was running it as a no water change system for 3 years almost (I know crazy). But now I started changing last two days. I don’t think changing water would overshoot my alk as I’m using tropic marine which has Alk at 8dKh. So surely replacing water that has 15dkh with 8dKh will reduce it overall? But will it cause a sudden drop if I do like 30% change?

I started carbon dosing vinegar and vodka 2 months ago with no help so far.

In terms of feeding it’s a small amount of pellets in the day and then 2 cubes of frozen in evening. The amount I add always gets eaten very quickly.

I have used both Hanna and salifert test kits with the same results.


I’ve started doing Elimi phos rapid since yesterday to help reduce phosphates down from 0.9. But I’m concerned what if my phosphates go down and then my nitrates don’t?

Really so lost on next steps lol

 

[Randy Holmes-Farley Verified Community Expert]

Not sure what the source is for phosphates and nitrates.

Foods. :)

It's just a matter of inputs being higher than exports and consumption.

 

[taki123]

Foods. :)

It's just a matter of inputs being higher than exports and consumption.

But I don’t think I feed that much. If I feed less I think it won’t be enough for my fish to survive.

 

[Randy Holmes-Farley Verified Community Expert]

But I don’t think I feed that much. If I feed less I think it won’t be enough for my fish to survive.

Eaten or not, most of the N and P in foods ends up in the water.

I did not suggest you were feeding too much. It might even be too little.

If you want nitrate and phosphate lower, you'll need to up the export in some fashion, of which there are a great many choices. :)

 

[BryanM]

I'd be mostly concerned with the alk parameter, but clearly all three need help. There's plenty of dirty tank threads that thrive, so thats why I say dealing with alk is most important.

 

[taki123]

I'd be mostly concerned with the alk parameter, but clearly all three need help. There's plenty of dirty tank threads that thrive, so thats why I say dealing with alk is most important.

I think that’s a big concern too but not sure what to do to reduce alk other than water change?

If I did a 30% water change with the new saltwater at 8dKh. Would that cause too much of a sudden drop in the tank given that is at 15dkh?

 

[BryanM]

I think that’s a big concern too but not sure what to do to reduce alk other than water change?

If I did a 30% water change with the new saltwater at 8dKh. Would that cause too much of a sudden drop in the tank given that is at 15dkh?

I'm not a numbers guy and I seem to screw up calculators. If it were me I'd probably start with 10% and measure the new alk so you'd get a feel for how much it would change.

I'm also pretty sure there's a way to calculate it.

This thread, and threads attached to it have good info:

https://www.reef2reef.com/threads/how-can-i-quickly-lower-alkalinity.712835/

 

[Randy Holmes-Farley Verified Community Expert]

I think that’s a big concern too but not sure what to do to reduce alk other than water change?

If I did a 30% water change with the new saltwater at 8dKh. Would that cause too much of a sudden drop in the tank given that is at 15dkh?

Did you measure the new salt water? Are you using tap water?

Did you dose alk up to that level?

If you did not overdose it, a likely way it got there is new salt water made using tap water, and so the new salt water may not be 8 dKH.

 

[taki123]

Did you measure the new salt water? Are you using tap water?

Did you dose alk up to that level?

If you did not overdose it, a likely way it got there is new salt water made using tap water, and so the new salt water may not be 8 dKH.

I use RODI with 0 TDS that I make my saltwater with. My ATO uses the same RODI which I’ve had tested also by ICP.

I am aware of why my alk and calcium are high which is due to me taking out a lot of GSP that was taking over my tank and keeping my dosing the same. So it overshot badly as there was a lot less coral to use it up but I was still dosing according to all that coral.

What do you think is the best way to reduce my Alk?