Low nitrates contributing to low Alkalinity?

[RyanO89]

Hey there quick question, I finally got my Hanna alk dkh tester and it gave me 7.6 which seems a tiny bit low. My tank has a relatively low bio load of two clowns, toadstool leather, finger leather, a few mushrooms and zoas, and a frog spawn. In total my tank has roughly 30 gallons of water and I do a weekly water change of 2 gallons. My nitrates are continuously 2ppm or less. Could my low nitrate and frequent water changes contribute to a lower alkalinity (saw a forum discussion mentioning nitrates role in maintaining alkalinity)? I currently use Instant Ocean Reef Crystals. Thanks all!

 

[Flippers4pups]

Hey there quick question, I finally got my Hanna alk dkh tester and it gave me 7.6 which seems a tiny bit low. My tank has a relatively low bio load of two clowns, toadstool leather, finger leather, a few mushrooms and zoas, and a frog spawn. In total my tank has roughly 30 gallons of water and I do a weekly water change of 2 gallons. My nitrates are continuously 2ppm or less. Could my low nitrate and frequent water changes contribute to a lower alkalinity (saw a forum discussion mentioning nitrates role in maintaining alkalinity)? I currently use Instant Ocean Reef Crystals. Thanks all!

I have never read of a direct relationship between alkalinity and N03. So you can have a undetectable N03 level and have high or low alkalinity. UNLS tanks have 0 N03 and typical lower DKH values around 7-8. Higher DKH in these systems can lead to burnt tips and bleaching.

There is a relationship between alkalinity and calcium in buffering capacity of PH.

 

[Gareth elliott]

What is your salinity?
Are you dosing at all or just doing water changes to replace ca/alkalinity?
If just water changes, your schedule may not be enough to fully replenish consumption.

 

[Randy Holmes-Farley Verified Community Expert]

Low nitrate does not cause alkalinity issues.

When nitrate is rising, alk will be depleted. When it is lowering, alk can be added.

These processes exactly offset if nitrate is steady (if you are not dosing nitrate).

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-12/rhf/index.htm

" the alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed."

"If nitrate is allowed to accumulate to 50 ppm, the addition of this acid will deplete 0.8 meq/L (2.3 dKH) of alkalinity."

 

[Az reefer]

Low nitrate does not cause alkalinity issues.

When nitrate is rising, alk will be depleted. When it is lowering, alk can be added.

These processes exactly offset if nitrate is steady (if you are not dosing nitrate).

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-12/rhf/index.htm

" the alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed."

"If nitrate is allowed to accumulate to 50 ppm, the addition of this acid will deplete 0.8 meq/L (2.3 dKH) of alkalinity."

Randy I have recently added a biodenitrator to my system and have gone from 25 ppm nitrate to 2.5 ppm over a 2 month period. I have noticed that my alk has dropped from 8.3 to 7.2 over this period. I run a calcium reactor and have had to continually adjust over this period to keep levels steady, being careful not to drift too high too fast.

 

[Randy Holmes-Farley Verified Community Expert]

Randy I have recently added a biodenitrator to my system and have gone from 25 ppm nitrate to 2.5 ppm over a 2 month period. I have noticed that my alk has dropped from 8.3 to 7.2 over this period. I run a calcium reactor and have had to continually adjust over this period to keep levels steady, being careful not to drift too high too fast.

A carbon denitor or a sulfur denitrator?

Sulfur denitrators deplete alk while carbon denitrators follow the above numbers I gave adding alkalinity.

 

[Az reefer]

A carbon denitor or a sulfur denitrator?

Sulfur denitrators deplete alk while carbon denitrators follow the above numbers I gave adding alkalinity.

It is a sulfur denutrator. That explains where the alk is going!!! Thank you Randy!!

 

[Randy Holmes-Farley Verified Community Expert]

It is a sulfur denutrator. That explains where the alk is going!!! Thank you Randy!!

That is a double whammy. You get the alk depletion as ammonia is converted into nitrate (2.3 dKH for every 50 ppm of nitrate produced) then you lose again when that nitrate is removed in the denitrator (about 1.5 dKH per 50 ppm nitrate consumed):

froom an article of mine:
Sulfur Denitrators

In these systems, bacteria use elemental sulfur and produce N2 from the sulfur and nitrate according the following equation (or something similar):

2 H2O + 5 S + 6 NO3– → 3 N2 + 5 SO42- + 4 H+

The production of acid (H+) in this reactor can tend to reduce the aquarium alkalinity.