Carbon dosing and phosphates

[Art2249]

I've been thinking about vodka dosing and need some advice. Right now my tank is 10 months old and the nitrates have slowly increased to 20 ppm. I do 5% bi-wwekly water changes. I have consistently needed to add phosphate to this tank over time. I generally try to keep it above zero but below 25 ppb. If I go a week without adding phosphate it will drop to zero. And things just don't look good when that happens. I had a green hair algae issue but started vibrant about 10 weeks ago. the vibrant has worked very well, although a couple corals didn't seem to like it much. Also I don't need to add as much phosphate as I think the gha was using it all up. I have dropped the vibrant dose to half. But i remember reading that vibrant would lower nitrates and i have seen the opposite effect. maybe because the gha is no longer taking up nitrate? I have 12 fish, most of them small but a couple that are approaching 3 inches. I feed about 1.24 inch square of reef frenzy twice daily along with 1 cube of mysis. the fish look healthy but always are hungry. The systm holds 200 gallons with 160 gallons being water.
So my idea is to switch from vibrant to vodka but I think I will need to keep dosing phosphate? Has anybody experienced a situation similar to mine?

 

[madweazl]

There have been points where nitrates were at undesirable levels while our phosphates were in a range I wanted to keep so I did some carbon dosing until the levels return to a range I wanted. That is a perfect case scenario for carbon dosing. With vodka, you may experience some cyanobacteria that you wouldnt get with vinegar. With vinegar, you may require enough to have short term lowering effects on your pH.

Based on the age of your tank, I'd bet your nitrogen cycle just hasnt completed yet and after a few more months, the nitrate levels will fall on their own because you arent feeding that much and you certainly dont have a high fish load.

 

[Holy_makerel]

The bacteria you feed with vodka use PO4 and NO3. If you dose it you run the risk of bottoming out your phosphates with little to no reduction in nitrates. I dose vodka but I only dose 2ml/day into a 60 cube. I have to feed fairly heavy to ensure I have a whiff of both nitrate and phosphate in the system. It's kind of a balancing act with vodka dosing.

If you decide to do it start very slowly and don't expect results for 4-6 weeks as the bacteria population increases

 

[Art2249]

There have been points where nitrates were at undesirable levels while our phosphates were in a range I wanted to keep so I did some carbon dosing until the levels return to a range I wanted. That is a perfect case scenario for carbon dosing. With vodka, you may experience some cyanobacteria that you wouldnt get with vinegar. With vinegar, you may require enough to have short term lowering effects on your pH.

Based on the age of your tank, I'd bet your nitrogen cycle just hasnt completed yet and after a few more months, the nitrate levels will fall on their own because you arent feeding that much and you certainly dont have a high fish load.

Thanks for the reply. It does seem like the tank is still going through phases. I had a tank back 25 years ago when things were much different. the only thing i could keep alive were softies. But back then I wasn't near as patient as i am now.