is it possible for nitrate to be 0 and phos at .04?

mos90

mos90

New member
i just purchaced a redsea pro n03 and po4 test kit to back up data from my hanna meters. my hanna meter was giving a reading of 3ppm nitrate and 14ppb phos. the phosphate tested the same on the redsea but nitrate tested zero 4 different times on 2 tanks. the redsea nitrate test kit is accurate enough to read the difference from 0 and .25ppm.

this on my 125g reef running a fuge,13 tbsp brs high cap gfo,750ml ecoback pellets. i do believe my no3 may be at 0 but im having a hard time with phos at .04. no matter what i do a cant lower it. i feed lightly 1 or 2 times a day.
fresh gfo every 3 weeks and 10% wc's every 2 weeks.

the only thing i can think of that may be causing higher phos is the dry ecorock from brs. ive heard of a few cases that it can leach phos for a while.

thoughts?
 
I've had bad luck with the Red Sea Pro Nitrate test kit-- no matter what, it reads zero and there is often a fine precipitate. I think the test needs either new instructions, or redesign. Trust your Hanna meter instead.
 
I have zero nitrates by Salifert and Elos tests. I have 0.27 phosphates by the Hanna Phosphate test. I do run bio-pellets and have a large amount of chaeto in my refugium.

My understanding is that chaeto and BPs remove a certain a ratio of nitrates to phosphates. Since we have 0 nitrates, the phosphates won't be exported. So I've started using Brightwell Aquatics Phosphate-E, and may start GFO in the near future.

Do you have any algae problem at all? You may be right that the BRS rock may be leaching phosphates (I read the same about Marco Rocks as well).
 
my tank is still young only 12 weeks. im getting some minor brown algea on the rocks and glass but not bad. the main thing im concerned about is do i really have 0 nitrate.
 
PO4 can be a PITA to lower and just takes patience. You might have rocks and substrate that can leach out accumulated PO4 for months, even new dead rock can be a PO4 reservoir. A PO4 level of 0.04 is pretty decent IMHO so if you can keep it there for a while you might be able to lower further. Some GFO experts can chime in but I think you could safely increase your GFO amount to see if you could drop the PO4, I realize you are using the high capacity stuff from BRS but I only have a 75 and I use about a cup and a half of Phosban. I think you only need to worry about lowering PO4 too quickly when you have inverts that are used to higher levels. Yours are already pretty low so it can't hurt to bump you GFO amount a little. I think Alk issues with too much GFO are only when using huge amounts or quick reductions in PO4 mess with the PH.
 
since ive started the system the po4 has never gone higher then .06. i should have no problem maintaining it at .02-.05 . im sure i could add a little more gfo. i think stripping phos to quick can also have a neg effect on sps corals.

if i didnt have sps corals i wouldnt even be concerned. i just dont want to starve them. but im scared to dose food or aminos and raise phos even more.
 
The biggest contributor to phosphate in your tank is fish foods and such. If your fish foods are high in phosphate and you feed to heavily, you can drive your phosphate level up high, even though your nitrate is low.

Hobby grade test kits are a notorious cause of headaches for hobbyists, especially for those parameters down in concentration to 0.03 ppm or only 30 parts per billion. This is an extremely low amount of phosphate to measure and hobby grade test kits can be off significantly. You need to use very clean test equipment when measuring at these levels, since a bit of contamination can throw off your results easily at ppb. ;)

You can always take a water sample to a trusted LFS and see if they get around the same results for your water parameters as you have. :)

I use the Hach PO-19 low phosphate test kit which is one of the better ones for phosphate, although the initial kit cost around $90.00, the refills are cheap. They have a new kit, the PO-19A which includes a filter mechanism for your sample water to remove things floating in your water that can falsely add to your phosphate level.
 
Hi mos90,
Usually, when using nutrient reduction methods (carbon source, refugium etc.) the NO3 will be the first to be depleted.


The residue, that forms on the bottom of the test kit's vial, is part of the chemical reaction.
Watch this short video, I hope it would help.

<iframe width="640" height="510" src="http://www.youtube.com/embed/Mf7jXkNBmX8" frameborder="0" allowfullscreen></iframe>

If there are any more questions, don't hesitate to ask on Red-Sea's Forum.
Enjoy your holiday weekend.

Aviad
 
FWIW, pristine coral reefs found in nature run at a phosphate level of around 0.005 ppm or 5 parts per billion. So it does not take much phosphate to have healthy coral. There are no hobby grade test kits that can read down to 5 ppb. You need very expensive lab equipment & the know how, to detect phosphate at natural reef levels. ;)
 
Keep in mind, that Dana Riddle is very knowledgeable regarding using testing equipment and is aware of the problems regarding suspended materials (organics) containing phosphate, contamination of test equipment, using more precise sample equipment.............etc. This can make a big difference when using any of the hobby grade test equipment for levels that low. ;)

FWIW, this is what Randy is referring too when he has stated in his test kit evaluation articles, where he states something to the effect that "In his hands the test kit worked satisfactorily for Reef Aquariums". :)
 
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HighlandReefer said:
Keep in mind, that Dana Riddle is very knowledgeable regarding using testing equipment and is aware of the problems regarding suspended materials (organics) containing phosphate, contamination of test equipment, using more precise sample equipment.............etc. This can make a big difference when using any of the hobby grade test equipment for levels that low. ;)

FWIW, this is what Randy is referring too when he has stated in his test kit evaluation articles, where he states something to the effect that "In his hands the test kit worked satisfactorily for Reef Aquariums". :)
Click to expand...

I agree but it's petty reasonable that if you are careful, rinse with good water and avoid dirty cuvettes your numbers should be reasonable. Garbage in garbage out. The way I look at it contamination is only going to make your numbers higher, significantly higher if you are sloppy, but if you get down into the 10ppb reading range on the Hanna ULR phosphorus, or near zero on row regular PO4 hanna, you are probably pretty good.

Just out of curiosity you think you could use coffee filters to pre filter on something like the Hanna checker to filter the sample? I generally throw out a sample if I can see anything floating in there but pre filtering might not be a bad idea like the Hach does.
 
Coffee filters, filter down to about 60-70 microns. That's about as small a particle as one can see with the naked eye. When chemists filter, they typically filter down to around 2.5-5.0 microns from my understanding & perhaps new techniques may filter down to smaller particles. Also there was a discussion a while back regarding using coffee filters and the material they are made of can interfere with some chemical test kits per Habib (owner of Salifert).

FWIW, one not knowing about testing equipment would be surprised regarding the equipment and methods used to simply clean test equipment. JDieck (author of the Chemistry Calculator) spent over $1000.00 on testing equipment quickly to try and get better test results using the more expensive meters available years ago. His final statement was to the effect that as long as his meter had an undetectable reading he was happy. :lol:
 
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i actually took the bio pellets offline on saturday. some of my corals were getting poor pe and didnt look happy. i made 2 changes just before i noticed this.

1) went from 500ml of pellets to 750ml.
2) i cut out the centers of my eggcrate tops to provide more light to corals.

i also have a lifereef skimmer. it is just tall enough that every time i need to clean the collection cup i have to pull the skimmer off the stand(pita). takes way to long. i havent cleaned it in a few weeks and i think it wasnt skimming properly. not a good thing with pellets. even though i love the skimmer i may sell it for 1 that fits under my stand better.

as far as the redsea test. i think i did it properly. there was a little residue on the bottom,.

so the question is, if my no3 is actually at 0 and phos at lets say .04 , would u feed your corals? would u consider those levels to a ulns tank?
 
forgot to mention the difference in par with the eggcrate top on and off.

on average with the eggcrate top on my par towards the top of the tank maybe 4" below the water line was about 350 and about 150 in the sandbed.

with the eggcrate off the top im getting nearly 450 4" down and 270ish in the sand. that sudden change could cause bleaching?
 
mos90 said:
i actually took the bio pellets offline on saturday. some of my corals were getting poor pe and didnt look happy. i made 2 changes just before i noticed this.

1) went from 500ml of pellets to 750ml.
2) i cut out the centers of my eggcrate tops to provide more light to corals.

i also have a lifereef skimmer. it is just tall enough that every time i need to clean the collection cup i have to pull the skimmer off the stand(pita). takes way to long. i havent cleaned it in a few weeks and i think it wasnt skimming properly. not a good thing with pellets. even though i love the skimmer i may sell it for 1 that fits under my stand better.

as far as the redsea test. i think i did it properly. there was a little residue on the bottom,.

so the question is, if my no3 is actually at 0 and phos at lets say .04 , would u feed your corals? would u consider those levels to a ulns tank?
Click to expand...

sounds like you need a new skimmer.
also it could be that you added abit too much pellets. especially if your getting low readings already. there will come a point that you can starve your corals out.

mos90 said:
forgot to mention the difference in par with the eggcrate top on and off.

on average with the eggcrate top on my par towards the top of the tank maybe 4" below the water line was about 350 and about 150 in the sandbed.

with the eggcrate off the top im getting nearly 450 4" down and 270ish in the sand. that sudden change could cause bleaching?
Click to expand...

yes sudden lighting changes can cause bleaching, but it could also be that your starving your corals. are you loosing colors? sps tips turning white? looking happy leave alot alot of room for error
 
fading colors, burnt tips, lack of pe and zoa's not opening all the way. i did have a minor alk spike from 8.8 to 9.3 over a 3 day period. im lowering it slowly. i dont think that that is enough of a jump to cause an issue.

im working with lifereef to see if he can make me a shorter collection cup. all i need is 1 1/2" shorter.
 
Getting a good read on PO4 below .04ppm may not be achievable since most test kits and meters have a range of accuracy around +/-.04ppm or.03.
With carbon dosing it is possible in an unfed tank to reduce nitrate to zero, but again test kits are unreliable at low levels so you may never know if it's 0.2, 0.5, 1 or actually 0.
The bacteria not only consume organic carbon along with nitrate and phosphorous in near typical ratios , they also engage in anaerobic digestion where the oxygen from the NO3 is stripped leaving some N to form N2 gas and bubble out. So more nitrate than one would expect relative to the carbon/nitrogen/phosphorous ratio is used.

The rock may also be leaching some PO4.

Many including me use gfo along with organic carbon dosing( vodka and vinegar in my case) to drop PO4 a bit further.
Just adding more organic carbon may lead to excess which can be harmful to corals,as it will not be used by bacteria starved for nitrogen and in dissolved form may not be exported by the skimmer as readily as when it's sequestered in a bacterium.

Running gac is also helpful in removing organics.
 
im thinking that as long as my phos is at or below .04 and no3 is less then 1ppm i will be fine. i really dont want to run levels too low.

for the time being im going keep the pellets online feed normally and see if nutirents rise.

normally i dose 20drops of elos aminos daily. i may keep dosing until i can verify some trace of no3.

i removed the gac yesterday i plan to replace it tonight.

im also leaving the mh's off for today. the actinics still provide over 100par in the sandbed.
 
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