Managing P&N in 340 gallon system

[Treefer32]

I must be missing something on large tank management. I see so many tanks doing amazing with no water changes and large tanks with just dosing going on. I've talked to other experts and people act like I'm crazy for thinking my P&N is unmanageable....

My tank is right at the 4 year mark and it's gone through many cycles over the years of things going well then corals dying off then doing well again. The biggest thing I've found is not alk fluctuations (That's constantly stable) or PH fluctuations, but honestly Nitrate and phosphate fluctuations. Just when I think I have everything under control and it's managed, it gets out of whack, and now my tank is coming back to tell me you know nothing about reefing or the ocean...

I've got a 5 gallon bucket of smelly black skimmate as a result of all my efforts over the last few months.

Filtration now includes:
1. been running for 5 weeks now large Bathshea Pellet reactor with 6-7 cups of pellets being turned over.
2. ATS Scrubber.
3. Dosing vodka until I run out and then slowly shutting that down to let the reactor take over.
4. Matrix Denitrifying rock in a cannister filter with water flowing over the rock and down through it
5. Bubble magus roller mat mechanical filtration (large 2400 gph flow rate).
6. Large oversized Diablo skimmer rated for 500 gallons.

Trends for Phosphates:

5/8 - .25
5/12 - .40
5/15 - .30
5/18 - .24

The only reason it's coming down is I'm dosing Phosphate - E (Lanthanum Chloride daily now 20 ml per day should reduce it by .2, but yet it's only dropping by .02 to .04 per day.

Nitrates:
5/1: 34
5/6 -28.5
5/12 - 28.6
5/18 - 37

As far as why Nitrates raised today is my skimmer cup got full and was shut off by my optical skimmer switch that detects if the skimmate holder is full or about to overflow. I'm wondering if that happened last night, and skimmer failed to run for around 12 hours. Which then, caused the nitrates to build back up despite all the filtration I have.

I'm going to get a nitrite test kit to validate something weird isn't happening with nitrite being detected as nitrates. I recently lost a gold hammer. Odd thing is I have an orange hammer in almost the same spot (same height flow, etc) 2 inches from the gold hammer, that has grown 4 new heads. Go figure.

I'm just trying to stop any coral loss / death due to hi P&N. In the past I've done 50% water changes. And it cuts P and N in half... for about 1 week. Then it's back to where it was and keeps climbing.

I can't do 50% water changes weekly. That'd be tough on everything (and me and cost wise $200 a month in salt alone).

Am I missing something or why is this so hard to do? What part of chemistry or organics / biology am I missing? Do I need a larger ATS (2 large 3 D growing units instead of one?) Do I need more pellets in the pellet reactor?

I'm looking for tried and true solutions vs. R&D. I thought the large pellet reactor was a tried and true solution, if it's working, it's very slow at it's job. It's been operational for 5 weeks now. The instructions say 3 weeks to be fully functional. Now that I'm at the end of the fifth week, Nitrates are rising instead of decreasing? Go figure!

 

[jda]

Do you have a sizable sandbed or a good amount of real/effective live rock? Both can be good at lowering nitrate to just a trace and thus completing the nitrogen cycle by turning no3 into nitrogen gas. Need 2-3 inches of undisturbed sand for this to happen the best.

Phosphate is more difficult since there is no bacteria that can remove it. Fuge, more skimmers work well for me but many have to use media for this - I throw out about 5 gallons of chaeto every few weeks. Another ATS would help.

Basically, need more details on the tank to help with solutions.

 

[Treefer32]

Thanks. I can get some pics too. May help.

Circulation: 4 Gyres, 2 on opposite ends of the tank pushing water at each other running at 80-90% 2 MP 40s pushing water from the lower back to the front.

Sand bed is 3-5" deep throughout the tank (My Dragon wrass is easily 1-2 inches thick and dives into the sand bed and buries himself. he also moves sand around daily. So, some areas may be shallower and others deeper. I originally put in 160 lbs of sand when I started.

Rock rock, around 150-200 pounds was in a previous 220 gallon system and then dried out in cold storage (froze got below zero temps, then heated up in the summer and then froze for around 2 years before I put it into the 340.)

 

[YOYOYOReefer]

not sure what a diablo skimmer if its a needlewheel on a tank that big you might want to get a bigger skimmer like a dual or quad beckett or a tall venturi skimmer.. or add a second needlewheel or 2,

 

[Treefer32]

This is the rebranded version. Mine is 8-9 years old, did replace the pump on it with the white DC controllable pump under warranty around 7 years ago.

 

[sixty_reefer]

I would just increase pellets and wait a couple more weeks to see what happens

 

[jda]

I have no idea why that sand is not chewing through the nitrate well. Perhaps it is gummed up with benign organics? I vacuum my sand every 3-4 years in small increments to get out that grey sludge that gums up the works. It does not have any organic value left that I can tell, but it does keep water from freely flowing and pods/worms/cirtters from doing their jobs in the area. Of course, I cannot get to it all, but I try and do small sections every few months until I get it all done in a year. This is all that I can think of.

As for the phosphate. The rock and sand likely has a large amount bound to it and is acting as a reservoir. As your remove it from the water, some unbinds from the rock/sand almost back up to the level that you were at. This is a normal behavior for aragonite or calcite. You just have to keep going with your methodology and eventually it will get lower.

 

[vetteguy53081]

Running large tanks, I utilize Chemipure Elite in the sump and algae scrubber

 

[jim_fitz]

apologies but being English i dont understand the amount of pellets that 6 cups is

I have approx 3 litres of pellets on my tank which is 3000 litres

 

[Treefer32]

I have 1500 ml or 1.5 liters.

 

[sixty_reefer]

apologies but being English i dont understand the amount of pellets that 6 cups is

I have approx 3 litres of pellets on my tank which is 3000 litres

I think 6 cups is around 1.4 litres

 

[Treefer32]

I have room to do at least double the pellets in the reactor. Does more pellets mean more flow and is there a cheaper place to get pellets? The ones I got were $70 for 1 liter of pellets. Seems really high if I need to be running 3 liters every 6 months.

 

[Randy Holmes-Farley Verified Community Expert]

I'm not a huge fan of biopellets.

They can take a long time to kick in and are much harder to alter doses and time the dosing than is a liquid organic like vinegar or vodka.

 

[nezw0001]

with my large system I run a sulfur denitrator and dose LC for phosphates.

 

[Treefer32]

I'm not a huge fan of biopellets.

They can take a long time to kick in and are much harder to alter doses and time the dosing than is a liquid organic like vinegar or vodka.

I agree Randy, I liked the control I had with Vodka. However, it was causing large clumps of organic matter throughout my sump. I think it was actually clumps of bacteria. I don't know. But, it was starting to plug up my intake of my return pump and it would collect on my gyres and gum them up. I couldn't control where the bacteria grew... The nasty slimy stuff that was on the blades of my gyres shut them down and damaged the rubber bushings on them. I didn't like not controlling where the bacteria grows. With the pelletized reactor I have the output of the water shooting right at the intake of my skimmer. My skimmer is now consistently producing skimmate. Before, it would produce skimmate at certain times of the day, then flatten out and produce no skimmate. Most likely allowing the bacteria to grow in clumps wherever it wanted to. I don't know if the pelletized reactor will be much better or not. I paid good money for the reactor. I hope it helps. . .

For now.. The phosphate E is helping to control the phosphates. They dropped down to .22 today from .24 yesterday. I'm dosing around 20 to 30 ml per day of phosphate-E. (Fairly large amounts...) I'm hoping to get them down to consistently under .1 then let the filtration control it and monitor more frequently. I had been monitoring once every 2 weeks or so, however, something caused it to start skyrocketing.

I looked into sulfur denitrators and it looks like they're really hard to dial in. And I couldn't find a reputable source for the media.

 

[Treefer32]

Nitrates continuing to rise, hitting a new high of 40.6 yesterday and phosphates slowly coming down with lanthinum chloride daily dosing about 20 ml per day. Phosphates around .15 ppm down from .40 ppm.

I'm going to have to go back to dosing vodka. I was able to keep nitrates stable at 25 ppm dosing 30 -40 ml of vodka a day.

 

[Treefer32]

Well, I've continued my quest of upping vodka dosing by 10 ml a week or so. I just upped from 50 ml per day to 60 ml per day today.

My phosphates have climbed from .11 to .28 ppm over the last 2 months (as of today).

Nitrates have climbed from 22 to 36 ppm as of today.

Alk remaining stable at 8.4 (usage has increased slightly).

Nitrate progression:

May 12th: 28.6
May 18th: 37
May 23rd: 40.6 (that's one crescendo there)
May 31st: 33.4 (Dosed MIcrobacter clean 1-2 days before and lower doses daily for a week per instructions).
June 5th: 36.3 (End of dosing of Microbacter Clean)
June 10th: 39.6 (Increased Vodka dosing to 50 ml per day from 40 ml per day)
June 16th: 36.1 (Slight decrease in Nitrates with increased vodka dosing) Upped Dosing to 60 ml per day starting today.

Phosphate Progression:
May 6th: .25 PPm
May 12th: .4 PPM (Dosed Phosphate - E for a few days starting here)
May 15th: .3 PPM
May 18th: .24 PPM
May 20th: .19 PPM
May 23rd: .19 PPM
May 25th: .21 PPM (Increased LC Daily dosing)
June 1st: .04 PPM (Stopped LC dosing all together and dosed Microbacter clean prior to this but after 5/25))
June 7th: .11 PPM
June 10th: .22 PPM
June 16th: .28 PPM (Today)


So, you'll notice it was nearly doubling after I stopped dosing LC.

My Hypothesis at this point is that Phosphates were increasing singnificantly until I nearly doubled my daily vodka dosing. Now, they only rose by 50% instead of 100%.

In theory, My proposal is that I'll need to get to around 70-90 ml per day of vodka dosing to get the phosphates managed at a lower level. Nitrates are on the downward trend right now. So, my hope is that with increased dosing nitrates will continue to fall and phosphates will stabilize and start to fall as well maybe a bit slower than nitrates.

I need a chemistry expert to let me know if I'm on the right track. Is 60-90 ml of vodka per day a lot to be dosing to a 340 gallon reef tank?

Right now at 50 ml per day, My ph was falling to 8.0 at night and 8.19 during the day. I'm scared, increasing the vodka dosing per day will lower PH further to the 7.8 range. . .

Maybe the tank adapts to the vodka and ph stabilizes over time?

 

[sixty_reefer]

I believe you may be 10ml away from seeing everything starting to come down, phosphates will take longer to drop as there will be some bound to the rock and substrate although you will see it coming down eventually after nitrates starting to lower.
What time of the day are you adding the vodka?

 

[Treefer32]

I'm using a BRS doser and on my apex. So, I'm doing almost every 2 hours 10-20 ml per every two hours. or so.

I do all daytime dosing while the lights are on:


Fallback OFF
Set OFF
If Time 10:00 to 10:05 Then ON
If Time 12:00 to 12:10 Then ON
If Time 14:00 to 14:16 Then ON
If Time 17:49 to 18:04 Then ON
If Time 19:00 to 19:12 Then ON

 

[Randy Holmes-Farley Verified Community Expert]

I would not assume vodka dosing to do all that much for phosphate. Usually the effect is small.