Nitrates and alkalinity

[Jetfixr]

I have a newer tank, about 3 months old. It seems to want to gravitate towards around 7.5dkh with a calcium of around 400. I have no room for a skimmer so I wanted to rely on denitrating and chaeto for nutrient export. I have about 2 liters of matrix, which is suppose denitrate. Also I have been using some chaeto. I never thought I would struggle to keep nitrate and phosphate level up, but I have already had to dose both to keep them from bottoming out. Not sure if it is the matrix or the chaeto burning up the nitrate. I am a little foggy on the nitrate/alkalinity relationship. Long term I would like to keep mostly LPS and polyps, and maintain levels with kalk, and shoot for cal of 425 with a 9 dkh of alk. I have turned down the light cycle on the cheato, it is growing like a weed. I really don't want to dose N and P, just doing so to keep my levels from bottoming out while I get this whole thing figured out. How can I keep my alk numbers more stable? It seems I set it at 9dkh and it quickly reverts to 7.5. I have used dry rock at this point there is no real algae, had a diatom bloom but it was handled quickly by my trochus snails.

 

[Jekyl]

I would toss out the matrix. Not a fan of adding things to the tank to fix problems.

 

[Doctorgori]

you got explosive coraline growth? you confident with your test kit?
I’m not aware of any chemical or biological relationship with alkalinity and nitrate except maybe fast growing corals….
waiting to hear other input

 

[Doctorgori]

I would toss out the matrix. Not a fan of adding things to the tank to fix problems.

I have some, can’t swear it does anything other than look like rocks and suspiciously similar to their denitrate product

 

[Jetfixr]

It is a hanna multi parameter test kit. Uses the same reagents as the checkers. The calcium test is a pain and from what I have heard, the calcium checker isn't terribly accurate so I am using a salifert kit for that. I am also using the matrix due to the display not having a whole bunch of rock. Using negative space aquascape, got tired of the huge pile o' rocks look.

 

[Dan_P]

I have a newer tank, about 3 months old. It seems to want to gravitate towards around 7.5dkh with a calcium of around 400. I have no room for a skimmer so I wanted to rely on denitrating and chaeto for nutrient export. I have about 2 liters of matrix, which is suppose denitrate. Also I have been using some chaeto. I never thought I would struggle to keep nitrate and phosphate level up, but I have already had to dose both to keep them from bottoming out. Not sure if it is the matrix or the chaeto burning up the nitrate. I am a little foggy on the nitrate/alkalinity relationship. Long term I would like to keep mostly LPS and polyps, and maintain levels with kalk, and shoot for cal of 425 with a 9 dkh of alk. I have turned down the light cycle on the cheato, it is growing like a weed. I really don't want to dose N and P, just doing so to keep my levels from bottoming out while I get this whole thing figured out. How can I keep my alk numbers more stable? It seems I set it at 9dkh and it quickly reverts to 7.5. I have used dry rock at this point there is no real algae, had a diatom bloom but it was handled quickly by my trochus snails.

You have two separate control issues. One is alkalinity, the other nitrate.

If you cannot keep nitrates up, having Chaeto and matrix to remove nitrates does not seem like the correct control strategy.

As for alkalinity, folks resort to dosing bicarbonate to maintain the level.

 

[reefGoat]

you got explosive coraline growth? you confident with your test kit?
I’m not aware of any chemical or biological relationship with alkalinity and nitrate except maybe fast growing corals….
waiting to hear other input

There is a link between nitrification/denitrification and alkalinity. I'm not a chemist and can't explain the mechanism. Maybe Randy will chime in.

 

[Randy Holmes-Farley]

I have a newer tank, about 3 months old. It seems to want to gravitate towards around 7.5dkh with a calcium of around 400. I have no room for a skimmer so I wanted to rely on denitrating and chaeto for nutrient export. I have about 2 liters of matrix, which is suppose denitrate. Also I have been using some chaeto. I never thought I would struggle to keep nitrate and phosphate level up, but I have already had to dose both to keep them from bottoming out. Not sure if it is the matrix or the chaeto burning up the nitrate. I am a little foggy on the nitrate/alkalinity relationship. Long term I would like to keep mostly LPS and polyps, and maintain levels with kalk, and shoot for cal of 425 with a 9 dkh of alk. I have turned down the light cycle on the cheato, it is growing like a weed. I really don't want to dose N and P, just doing so to keep my levels from bottoming out while I get this whole thing figured out. How can I keep my alk numbers more stable? It seems I set it at 9dkh and it quickly reverts to 7.5. I have used dry rock at this point there is no real algae, had a diatom bloom but it was handled quickly by my trochus snails.

There's no need or benefit to keeping alk at 9 dKH as opposed to 7.0 dKH in a tank without corals. It just uses alkalinity supplements faster because it takes more every day to keep alk higher.

9 dKH is a fine target for later, but for now, let it drop.

 

[Randy Holmes-Farley]

There is a link between nitrification/denitrification and alkalinity. I'm not a chemist and can't explain the mechanism. Maybe Randy will chime in.

When nitrate is produced from ammonia (e.g., from foods), alkalinity is depleted to the tune of 2.3 dKH depleted for each 50 ppm of nitrate produced.

Likewise, when nitrate is consumed in any fashion (except removed by water change), that amount of alkalinity is exactly added back.

Thus, if nitrate is steady at any level (and not being dosed), it is having no ongoing impact on alkalinity.

If you are dosing nitrate and it is consumed, you effectively add 2.3 dKH for each 50 ppm of nitrate dosed and consumed.

 

[Jetfixr]

Thanks Randy, good info to have, looks like at my levels it isn't a huge deal, I remember u mentioning there being a correlation between Alk and nitrates. I just didn't understand what it was, now I know....Interesting!! Currently I have a frogspawn, and a torch, a few fish and a CUC. Minimal Kh demand, but as I get more LPS and coralline starts to kick in, I will be looking to raise the level a bit. Appreciate the info.