Redfield ratio details

BradB · Feb 23, 2016

Ran another Hanna ultra low check before starting. 31 ppb Phosphorus = 95 ppb phosphate, yikes! It kept reading 0, but I knew the tank had phosphate, so I stopped checking.

Started with my standard marked vodka dose for how much to add daily to lower nitrates when they are a high (most of the past 5 years). I weighed this as 14 grams of vodka, which has about 4.3 grams ethanol. Did my best to measure 4 grams of stump remover, dissolved in RO water, added that first, let it mix, then added the vodka. Now I am waiting to see what happens.

Randy Holmes-Farley · Feb 24, 2016

OK, let us know what happens.

BradB · Feb 24, 2016

I expected either my skimmer to go crazy, or to see a ton of algea. I've been underwhelmed so far. After my 2nd dose, absolutely nothing observable has happened. I also switched to 1/2 tbp potassium nitrate instead of trying to measure weight with the scale I have. This weekend, I plan to measure Nitrate and phosphate again, recharge my gfo, and possibly up the dosage.

BradB · Feb 25, 2016

Day 3, still nothing observably different. My yellow tort is looking worse, but it has been looking bad since December. Everything else looks the same, including skimmate and algae.

I did measure phosphate again. Surprisingly, the main tank is down to 2ppb Phosphorus / 6 ppb Phosphate. My GFO reads 11 ppb Phosphorus / 33 ppb Phosphate. I don't know what this means.

Does this mean my GFO is exhausted and leaching back into the tank, since it is higher than the tank? Or does this mean my GFO is good, since 11 ppb really isn't that bad?

Does this mean what I dosed lowered the Phosphate? Or does this just mean my Hanna checker has a high variance?

Randy Holmes-Farley · Feb 26, 2016

If you did get the phosphate lower in the tank than the GFO was previously equilibrated with, phosphate would come off it, but I can't tell if that is what you are seeing, or just random error, as you noted was possible.

I'd measure both again, and if the GFO effluent was higher than the tank a second time, I'd remove it.

BradB · Feb 27, 2016

Today, the main tank was 6/18 and the GFO read 59/177. So I pulled the GFO and am going to regenerate. I just added a BRS Jumbo with fresh GFO at the beginning of February, and things started to look better for a while. I guess I exhausted it already.

BradB · Feb 28, 2016

Today I found my DI resin was also exhausted. I run RO into a 30 gallon reservoir, which was about 20pmm TDI. The water coming in was 60 ppm TDI, so I guess I caught it early. From my RO, I am about 25ppm, and street water is about 500ppm.

Measured nitrate for the first time today. I am at about 3ppm, and that is 6 hours after dosing nitrate without dosing the vodka. So what I am doing is working, at least as far as not becoming a nitrate problem.

BradB · Mar 16, 2016

Someone local was selling a Heteractis magnifica in captivity for years. I normally would add new animals to the tank when it is like this, but it has been on my wish list for 5 years or so. The seller told me high nitrates would be deadly but Phosphates won't be a problem. So I took a week off this experiment and measured again today.

Phosphate are up to 79/237 ppb again. I can't figure this out. I do have a lot of fish, and I do feed a lot, but this hasn't changed in the past 3 years. Nitrates are not detectable (using a Hatch test kit, I normally used Salifert). Phosphate coming off GFO measured 5/15 so that isn't the problem. I did clean my powerheads and added an Jebao RW-20 to increase flow for the mag. Perhaps I kicked up something? This was a relatively high flow tank before. I added my usual Nitrate and Vodka.

I am considering adding a permanent mixture of potassium Nitrate and Vodka to my doser. I've already gone through about 300 grams of Potassium Nitrate.

Randy Holmes-Farley · Mar 17, 2016

300 grams. Wow!

Assuming you are back to 0 ppm TDs water, I think the answer is just that you have a lot of denitrification and not enough phosphate export to match it.

I presume you have a skimmer?