nitrate issue

[ultramud]

hi ATJ
Long time no see, hope all the tanks are all powering on.
i've got a quick question of the water quality nature?
heres some background info,
5*2*@ tank 100l sump * 2
DSB(in tank) has been cycling for 3 months, I added 30kg of cured rock + a bit of live sand 6 weeks ago and the 15 kg of uncured 3 weeks ago.
lights have been up for about 10 weeks, photo = (14 hrs * floros, 2hrs * mh)
skimmer going constantly for 3 months pulling nice thick sludge.
and only i water change a month (200l)
feeding: around 2 cube's of frozen marine crap/ week(slowed down with the uncured rock)

ive been testing the water weekly with test kits and have been getting good results (nitrates at 0-5 )
i then take a sample to work and get the guys there to test it for me.


sample was taken at 5 in the morning so i expected ph and alk to be a bit wobbly
ph 8.1
alk 141
ca 661
ammonia 0
nitrites 0
phosphates .19
NITRATES 19.4

a bit different from the kits(seachem, dupla, seara)poxy kits
im sure the tank is still cycling but im concerned that the nitrate are an indication of what the tank will be like in the future( maybe i stuffed up the DSB?)any ideas? im also going through a mild but constant cyano bloom is this eating off the nitrates? in my understanding water changes will help in the short term but still 19.4??????
i plan to convert 1/4 of the sump into a macro/micro/?????? fuge in the future to deal with the nutrients from a stocked tank but 19.4????????????? with out any fish

any advice would be muchly appreciated.
cheers
Matt

p.s. can you tell the nitrates are killing me

[ATJ]

G'day Matt.

The tank is still young and I would expect some nitrate until denitrification really kicks in. If you have had any dieback on the rocks you would have had ammonia and nitrite that would have been converted into nitrate. If there was a lot of ammonia and nitrite your reading would not be that unexpected. And with only 2 or 3 200L water changes tops...

Have you tested your top up water and mixed water ready to go?

[ultramud]

for top up water i use the towns potable water which is bore water for the great artesian basin run through an r/o unit. test kits say every thing is ok(0-5ppm nitrates)no copper(seeing as i work in a copper mine)
as the tank is still fishless i didnt expect the lab results to come back so high for the nitrates, i was expecting 5-10ppm but as you said the tank is still young. ill just have to be a bit more patient.
i didnt mention circulation. 6cubes/hr turbella stream, 2 *1cube maxijets, 3.5 circ pump + skimmer.
ive read that some lps's(ancora ect) like nutrient rich water? have you had any experience with this. i cant find the article but was thinking of making a bit of room in my other tank(totally overcrowded) by throwing a frogspawn and an ancroa in
or again is this too soon

thanks for you help

matt

[ATJ]

Matt,

Have you tested the bore water at work? Sounds like you are getting the same readings for it as you were for the tank with your kits.

[ultramud]

tell me about it, according to the test kits i have a perfect tank every time regardless if im cycling a new one or not?????
i fowarded this Q to anthony calfo as i thought you might be on holidays or somthing and he picked up on a very good point.
the test the lab did for me might be reading nitrates as nitrogen where the hobby kits read ions. this would bring things down to a reasonable level (oround 4ish), ill have to have a chat to them tomorrow.
what do you think about the LPS's have you read or herd info like this??

cheers
matt

[ATJ]

Matt,

It works the other way around. If you have a reading of 19.4 mg/L for NO₃-N (19.4 milligrams of nitrogen per litre as nitrate), the NO₃ concentration is 77.6 mg/L. A nitrate ion is 4.4 time heavier than nitrogen on its own: (14 + 3*16)/14. So, NO₃ of 19.4 mg/L is not good, but NO₃-N of 19.4 mg/L is 4.4 times worse.

I have not found the Seachem nitrate test kit to give any sort of reading that makes any sense. I have not tried Sera or Dupla, but I would not trust them either. Salifert is the only hobbyist kit I would trust for nitrate.

There is some anecdotal evidence for some corals tolerating higher nutrient levels than others. It should be noted, however, that natural reefs have very, very low nitrate concentrations. Basically, if you can measure nitrate with a hobbyist kit, you have more nitrate than even some polluted reefs. A nitrate reading of 5 mg/L is significantly higher than you'd ever find on a natural reef.

That said, nitrate is pretty harmless, in my opinion. It has been found to inhibit calcification as low as 0.06 mg/L, but it appears that concentrations over 0.3 mg/L do not further inhibit calcification. That is, aim for undetectable nitrate, but if it is higher than 0.5 mg/L, it is not going to make a lot of difference if it is 1, 10 or 30 mg/L. It is possible that high nitrate may give the corals less control over their zooxanthellae, so you should still aim for as low as possible.

[ultramud]

moral of the story
wait
ill let thing go for a few more weeks then try again
cheers
matt