Vinegar dosing minimums?

[mikellini]

I've read that dosing too little organic carbon has very little effect on N&P reduction, but that the range between just enough and too much is very large. So, I'm trying to find out what the minimum amount is that I need to dose to start reducing nitrates. I've also read that anything up to about 1ml/10 gallons of vinegar is OK to dose all at once, while more than that should be spread out so as to minimize the effect on pH. So right now on my ~100 gallons of water volume, I'm dosing 6ml of vinegar per day (I know this is a small amount). I started with 4ml/day for two weeks and saw no change, nitrates between 4-8ppm...

My question is this: am I doing anything by dosing 6ml of vinegar? Or do I need to hit a minimum threshold to have an effect on nitrate reduction? And if I need to hit this threshold, will it likely be below 1ml/10 gallons, or am I going to have to start dosing twice per day? Right now I'm doing this manually, but eventually I'll get a dosing pump going...

Also, one more question. Is there much of a difference between dosing 10ml once daily, versus dosing 1 ml ten times daily?

 

[BrotherReef]

From what I understand is you keep increasing your dosage weekly until you see the reduction in your nitrates and then once you achieve your goal you cut it in half and that's your maintenance goal.

When I was doing vinegar I did multiple doses for more consistency.

 

[Randy Holmes-Farley]

There is no minimum threshold, although you won't notice effects if the dose is low.

Any amount will encourage bacterial growth, and that growth uses N and P.

Since the exact amount that is optimal for any given reef will vary, that is why many folks slowly increase the dose over time, noting effects such as nitrate, phosphate, algae growth, or other tank effects.

The pH can drop with vinegar dosing, and so many people spread out the dosing. Alternatively, you can add calcium hydroxide directly to the vinegar so it won't cause any immediate pH drop. I did that when I started dosing it.

 

[Randy Holmes-Farley]

Do you have a pH meter too nitro the effects?

 

[mikellini]

Do you have a pH meter too nitro the effects?

I don't have a meter, and don't typically check pH anyway... How much calcium hydroxide would I add to a 60ml syringe to mitigate the change in pH? And would this be enough to affect calcium and alkalinity at a dose of, say, 20ml per day on my 100 gallon volume?

 

[Randy Holmes-Farley]

The way I did it was to take a 1 gallon jug of vinegar and add enough calcium hydroxide to saturate it, meaning some solid is left on the bottom. How much is left over doesn't matter.

Then just use the clear liquid above, which will have a pH much higher, like pH 12, and so won't drop the tank pH at all, and the pH boost to the tank is small enough to not worry about for any amount of vinegar you'd choose to add.

It won't add enough calcium and alkalinity to be a big driver, but it will add some.

100 ml added to 100 gallons will boost alk by about 0.6 dKH.

 

[mikellini]

Would I then be able to dose a set amount of the vinegar kalk via a dosing pump? Sounds like it'd be a more reliable way to dose kalk than through and ato, and may provide enough supplementation to reduce the need for dosing two part. What is the difference in concentration between vinegar kalk and kalkwasser?

I can see that I might add more through my ato than my vinegar dose would be, but if the concentration is higher would they put in close to the same amount of calcium hydroxide?

 

[Randy Holmes-Farley]

Well, I'm not sure the "more reliable" part is clear, but it is certainly fine to dose the vinegar/lime with a dosing pump.

Using vinegar/lime will only slightly reduce the dose of the two part, unless the vinegar dose is pretty high, but yes, it will.

Per unit of volume, the vinegar/lime is much more potent than ordinary limewater, or even limewater with vinegar, but folks add far less of the vinegar lime.

I add a few gallons of limewater each day, and at the highest dose I ever used (which was too much), I only dosed 410 mL of vinegar. I currently only dose about 110 mL of vinegar.

 

[mikellini]

I was just thinking more reliable in that you're dosing exactly the same amount every day, vs dosing based on evaporation, which can change a fair bit with the seasons at least.

Thanks for the info, I'll try it!

 

[mikellini]

Randy, what is your total water volume that you're dosing that 110ml of vinegar into?

 

[Randy Holmes-Farley]

I have a 120 display with about 300 gallons total.

I know people worry about variable dosing and that may be well founded in some cases, but limewater by ATO is the only way I've dosed my tank for the past 19 years.

 

[mikellini]

One more question Randy; how much lime will I need to saturate a gallon of vinegar?

 

[BrotherReef]

So what is the ratio of vinegar to lime to RO/DI water you use Randy?

 

[Randy Holmes-Farley]

One more question Randy; how much lime will I need to saturate a gallon of vinegar?

About 250 grams. Adding more is fine and just leave it on the bottom.

 

[Randy Holmes-Farley]

So what is the ratio of vinegar to lime to RO/DI water you use Randy?

I use limewater that is a bit under saturation as top off, and I dose straight vineger with a dosing pump.

A few gallons of limewater (depends on the season), and 110 mL of vinegar (no lime) each day.

 

[mikellini]

Good info, thanks!

 

[BrotherReef]

Ok. But I think I explained myself wrong to you mainly because I red it wrong. I was thinking as for top off water your lime water ratio to Ro/DI water.

 

[Randy Holmes-Farley]

Saturation is about 2 level teaspoons of calcium hydroxide per gallon of fresh water. I don't actually measure it that way, but rather by conductivity, where saturation is about 10 mS/cm, and the dissolved concentration is about linear with the conductivity below that,

But most people use saturated or near saturated limewater, unless there is very little demand in the tank.

 

[BrotherReef]

Thank you sir. Makes better sense.

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.