Nitrates and Phosphates - Water Change %

[Randy Holmes-Farley Verified Community Expert]

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?

Green Star polyps do not consume alkalinity, but certainly if you were dosing, that could drive it up if messing with the tank drove down demand. .

How long has it been up? I'd be typically inclined to let it fall on its own.

Try the kit on some new water to be sure there's not a testing issue.

You can lower the alk in new salt water to make water changes even more effective at lowering alk without wasting a lot of salt water.

 

[taki123]

Green Star polyps do not consume alkalinity, but certainly if you were dosing, that could drive it up if messing with the tank drove down demand. .

How long has it been up? I'd be typically inclined to let it fall on its own.

Try the kit on some new water to be sure there's not a testing issue.

You can lower the alk in new salt water to make water changes even more effective at lowering alk without wasting a lot of salt water.

I have no idea how long it’s been up now. I was neglecting and not testing for a while unfortunately.

I tried the kit on my new saltwater and the alk seemed to be in line with what the salt says. Ibe also tested with 2 kits Hanna and Salifert with the same results.

 

[Randy Holmes-Farley Verified Community Expert]

Do you have a picture of the tank so we can assess likely alk demand, to determine if just waiting will work?

 

[taki123]

Do you have a picture of the tank so we can assess likely alk demand, to determine if just waiting will work?

Sure let me send photo. Sadly I think my minimal coral won’t use up the alk lol.

Let me know your thoughts.

 

[BryanM]

Minimal in number, but not in size!

 

[Randy Holmes-Farley Verified Community Expert]

I’d personally just watch for a few days, checking alk every couple of days.

 

[taki123]

Minimal in number, but not in size!

That’s true but no idea if they’ll use up my alkalinity lol

@Randy Holmes-Farley what do you think.

 

[Randy Holmes-Farley Verified Community Expert]

That’s true but no idea if they’ll use up my alkalinity lol

@Randy Holmes-Farley what do you think.

I’d just wait and watch for a while.

 

[taki123]

I’d just wait and watch for a while.

But should I carry on daily 15-20 water changes meantime?

 

[Randy Holmes-Farley Verified Community Expert]

But should I carry on daily 15-20 water changes meantime?

I personally would not. Bringing down alk and nitrate too fast is more likely to cause a problem than help one.

 

[taki123]

I personally would not. Bringing down alk and nitrate too fast is more likely to cause a problem than help one.

Hmmm but based on my last two water changes my alk only went down by 0.1dKh and nitrates not at all.

It’s all just very weird

 

[Randy Holmes-Farley Verified Community Expert]

Hmmm but based on my last two water changes my alk only went down by 0.1dKh and nitrates not at all.

It’s all just very weird

If the new salt water is 8 dKH and the tank is 15 dKH, then a 20% water change must result in 13.6 dKH. Anything else is a test or volume measurement error.

 

[taki123]

If the new salt water is 8 dKH and the tank is 15 dKH, then a 20% water change must result in 13.6 dKH. Anything else is a test or volume measurement error.

That’s actually true. Unless my DIY vinegar vodka is increasing it?

 

[Randy Holmes-Farley Verified Community Expert]

That’s actually true. Unless my DIY vinegar vodka is increasing it?

Vinegar and vodka cannot boost alk.

 

[KrisReef]

That’s actually true. Unless my DIY vinegar vodka is increasing it?

As a person who has seen many undesirable results from rapid number changes I can easily recommend that you use the vinegar on your salad and the vodka in your drink.

Did you recently start testing after years of being on cruise control? That would allow phosphate load in the tank to grow to what you have now. The corals look happy, and changing ALK and P & NO3 is likely to end up making the corals unhappy and may not get after your algae issue either (and it doesn't look that bad, but I understand you are seeing it more than I am.)

Slow down. Phosphate binds to the substrates in the tank and removing all the water, (100% WC) could get you close to zero P on day one, but P might bounch back in a week to almost the same 9.0 number you have now as the bound up P moves off the substrates and into the clean water!

So, Find a product that binds phosphates and use it carefully to slowly absorb and remove the excess in the next few months.

 

[taki123]

As a person who has seen many undesirable results from rapid number changes I can easily recommend that you use the vinegar on your salad and the vodka in your drink.

Did you recently start testing after years of being on cruise control? That would allow phosphate load in the tank to grow to what you have now. The corals look happy, and changing ALK and P & NO3 is likely to end up making the corals unhappy and may not get after your algae issue either (and it doesn't look that bad, but I understand you are seeing it more than I am.)

Slow down. Phosphate binds to the substrates in the tank and removing all the water, (100% WC) could get you close to zero P on day one, but P might bounch back in a week to almost the same 9.0 number you have now as the bound up P moves off the substrates and into the clean water!

So, Find a product that binds phosphates and use it carefully to slowly absorb and remove the excess in the next few months.

Basically has been on cruise control for a while yes. But the reason for carbon dosing is to reduce Nitrates more than phosphates. For phosphates I started dosing Elimi Phos Rapid since 2 days ago.

In regards to water changes I’ll just change twice a week or so and see how things go.

 

[t5Nitro]

Successful reef tanks out there with N and P similar (and sometimes higher) to yours. I wouldn’t sweat those as much as others have pointed out getting your alkalinity back to a proper concentration, slowly.

 

[backbayreef]

Basically has been on cruise control for a while yes. But the reason for carbon dosing is to reduce Nitrates more than phosphates. For phosphates I started dosing Elimi Phos Rapid since 2 days ago.

In regards to water changes I’ll just change twice a week or so and see how things go.

I'm fighting to reducing my nitrate as we speak. My frag tank has been on auto-pilot for 18+ mos and I want to finally grow SPS frags. Nitrate was 232 and carbon dosing (20ml/day of vodka on a 90gal tank) was not keeping up after 5 weeks! I've done a 50% WC and nitrate dropped to 149 but quickly bounced back to 170. If you're measuring 75 from your Hanna HR Nitrate, that means you'll need to dilute it get a better number. I've used 25% tank water and 75% newly mixed water.

I just got a sulfur-based denitrator reactor online 4 days ago and nitrate is down to 65 inside the reactor. It will take several weeks to process the whole tank but I'm optimistic that this will come down.

Phosphate reduction was super faster & easy for me -- I use PhosphateRx. Just go slow on this one and make sure you have 10micron filter/fleece or dump inside skimmer body. Get down to under 0.1 but don't bottom out.

Good luck!

 

[taki123]

I'm fighting to reducing my nitrate as we speak. My frag tank has been on auto-pilot for 18+ mos and I want to finally grow SPS frags. Nitrate was 232 and carbon dosing (20ml/day of vodka on a 90gal tank) was not keeping up after 5 weeks! I've done a 50% WC and nitrate dropped to 149 but quickly bounced back to 170. If you're measuring 75 from your Hanna HR Nitrate, that means you'll need to dilute it get a better number. I've used 25% tank water and 75% newly mixed water.

I just got a sulfur-based denitrator reactor online 4 days ago and nitrate is down to 65 inside the reactor. It will take several weeks to process the whole tank but I'm optimistic that this will come down.

Phosphate reduction was super faster & easy for me -- I use PhosphateRx. Just go slow on this one and make sure you have 10micron filter/fleece or dump inside skimmer body. Get down to under 0.1 but don't bottom out.

Good luck!

What do you mean by nitrate down inside the reactor? Doesn’t it just keep pulling water in and pushing it out? Do you mean your tank water is now at 65?

To test with the Hanna by newly mixed water do you mean newly mixed saltwater or RODI?

 

[backbayreef]

What do you mean by nitrate down inside the reactor? Doesn’t it just keep pulling water in and pushing it out? Do you mean your tank water is now at 65?

To test with the Hanna by newly mixed water do you mean newly mixed saltwater or RODI?

Correct — incoming water is still 140+ but the effluent is 65. I’m dripping at only 10ml/min.

Either. You can do RODI — take the result and multiply by 2 if you’re diluting 50:50 tank water:RODI.