So I have a nitrate issue I can not seem to get to the bottom of. Tank is 2 year old 47G AIO. I run filter socks, 2 protein skimmers, and 2 Nero 5 wave makers. Stock list is 3 smaller clowns, 1 yellow watchman, 1 mandarin, and 1 medium blue eyed Kole, pistol shrimp, dozen or so hermits, and mixture of snails. I feed a small piece of nori every other day and 1/5 a cube of mysis a day. Socks are cleaned religiously every two days. Skimmers run 24/7 more on the wet side as far as skimate goes. Dose tropic Marin np bacto balance .4ml every night at lights out. PO4 stays 0.04-0.07 My nitrates according to Nyos kit were running 20-30ppm, I was fine with that. Then NO3 started to climb despite doing 5 gal water change every week with 0ppm nitrate rodi. I switched to Tropic Marin elmi np monitoring PO4 to maintain at least 0.04 by dosing. NO3 got to around 95ppm mark. I them purchased a Hannah HR nitrate checker to verify it wasn’t a test issue, flashing 75. Diluted down to 9ml of rodi and 1 ml of tank water, reading then was 31.1 so multiply by 10 to be 311ppm. Verified this with 4 test 2 different batches of reagent. I then performed a 40-45% water change and got them down to 179ppm. I then began a routine 25% water change every 4 days and now have NO3 down to 133. My issue I can’t figure out is why my nitrates are raising 10-15 ppm every 3 days, I’m calculating out to a 3.5ppm increase per day. Nothing has died, flow is good random pattern of 1100-1500gph to keep from detritus build up, feeding to me is very minimal, export with socks and 2 skimmers I would believe to be overkill and dosing 0.6ml of elmi np for 8 weeks. What am I missing or any suggestions?
A skimmer isn't going to help much at all with dissolved nutrient levels, regardless of tuning or maintenance routine, but I'm still curious why you have two skimmers? Would a single unit be preferred since it would take up less space and be a little more efficient than two?
Here's the thing...
Dissolved nutrient levels correspond to feeding levels.
Feeding levels are dictated by your quantity (mass) of livestock.
Your tank is overstocked by most conventional definitions.
As a result you are overfeeding the tank in comparison to what it can process (not necessarily related to tank size) – this is how dissolved nutrients happen.
You might ALSO be overfeeding beyond what your livestock needs OR things that are not being well-utilized...mandarin and coral feedings are notoriously bad on this, just for two examples.
FYI, "export" can only mop up after "the mess" has been made. To prevent problems (eg algae blooms, etc) you will want to prevent the mess from happening instead cleaning it up afterward.
And if you aren't having any problems (Ie. if you're just trying to change the numbers on the test kits) then be careful about any changes you make. "High nutrients" aren't a problem
per se....plenty of killer reef tanks out there have nutrient levels that are
crazy high compared to what's typically been preached in the hobby. It's helpful IMO to remember that nitrogen and phosphorus are essential major nutrients – not "waste" or "toxic" or whatever. The distinction will help with understanding when something does go wrong. For example, it's more likely to be a problem if you have "zero nutrients" than if you have "high nutrients".
Real reefs do not have "zero nutrient" water, and the only reason water tests show low numbers
at some reefs is from the reef using and recycling up 99.9% of the available nutrients.....NOT because there are no nutrients...not even because the water is clean....almost the opposite....the reef is there because of the available nutrients, but it's such a perfectly efficient ecosystem that the water is the way it is once the reef is established. This "clean" water is a
result of the reef, not a precondition for it.
IMO, make
sure you aren't wasting food in the tank. Broadcast feeding wastes A LOT if you are doing that...switch to target feeding, incidental feeding or figure something else out. If you are
sure you aren't wasting food, then consider reducing the amount of livestock in the tank.....personally I'd re-home the Tang since the tank is not the right size for it anyway, but reduce livestock mass somehow. Less livestock = less feeding = less dissolved nutrients.
I would discontinue things like carbon dosing if you're still doing any "extras" like that. Reduce nutrient inputs and the problem will resolve on its own (and respond better to your cleanup efforts).
