Questions on Nitrate & KH levels

[SeaHorseQueen]

Hey, I've been battling out nitrates for a while but it's been far better than before. I have a salifert KH/Alk test and hanna High Nitrate checker.

My past nitrate readings has been the max amount measured and blinking on the hanna checker. Would phosphates cause the higher KH? I know it affects nitrate. Does anyone know what might be happening? I'm working to keep the salinity between 0.23-24. My hammer is doing good. GSP isn't coming out right now. I did a 75% water change just before the weekend so it's had enough time to lower the levels. I can't seem to get it in the normal range on nitrates. I do have to buy a phosphate test this week.

This is what I'm at before topping off the water tonight.

Nitrate: 56.2
KH: 10.5

Tests after topping off an almost 2hrs after. I'll update tomorrow night for 24hrs.

Nitrate: 52.5
KH: 11.5

Tank information: 20g high, 35lb live rock (5-6lbs is new 1.5 weeks ago), 2yrs 8 months old, HOB filter with built in skimmer (150-180mpg), 1 clownfish, CUC (1 turbo snail/2 dwarf hermit crabs), and one Mandarin Dragonet. Yes, I have copepod cultures running full force and have plans to finally transfer it to a 50 or 75g by the end of the month. I'm looking at taking both top and bottom braces off the 75g I have and have it deep cleaned. Or I may just scrap the 75g and get a new one since Petco has them 50% off. It's finding a true sturdy tank stand that bothers me with the 75g as I want one with doors for storage and a 10-20g skimmer underneath hidden. The biggest I've ever had was a 55g freshwater tank but after the roof collapsed at my parent's home (before I moved out) I had to sell it because debris crashed into the tank as well. I didn't have a place to put it so someone might as well have gotten some use for it.

 

[Randy Holmes-Farley Verified Community Expert]

Nitrate itself doesn't impact alk, but rising or dropping levels will. A change of 50 ppm in nitrate causes a change in alk of 2.3 dKH, unless accomplished by water change.

Phosphate itself does impact alk directly, but the levels of phosphate are always so low that the impact is insignificant.