Low nutrients, normal pH and slightly elevated Alk

pdiehm · Jan 31, 2016

I have been reading. A LOT of reading. Most of which I don't understand. But what I have read that I can actually remember and out into some form of English language...

Lower the nutrients, the lower the alkalinity you want.

What I read is 0 NO3, PO4...well as low as the test kits we have at our disposal can go...you typically want a dKh under 8.3.

If you have slightly elevated PO4, say 0.05, and NO3 under 5, you want a higher alkalinity of say, 9.5-11.

Or am I missing it?

Right now I tested 0/0, with pH of 8.2 and alkalinity of 9.5...a little elevated from what I have read, but I have battled cyano and won. I battled dinos and I have very much either defeated and/or won that battle, but my levels were somewhat elevated when I started to dose with kalk. Since I have reduced the nutrients, I have stopped dosing kalk.

I guess I am afraid of a side effect of having a raised level of alkalinity (albeit it slightly) in conjunction of my low nutrients.

Cory · Jan 31, 2016

Thats a general thing said by reefers to have lower alkalinity with low nutrients. The tips of sps can receed in those conditions. Probably because they need the po4 and no3 to build tissue while the skeloton grows upward. Thats where exsposed tips come from. However this is not true for all tanks. A factor would be lighting too. High intensity light with high par values would increase growth rate but without enough nutrients... Same thing. These are my opinions.

So you got factors like food, lighting, water flow, and nutrient concentration which all differ from tank to tank.

Randy Holmes-Farley · Feb 1, 2016

pdiehm said:
I have been reading. A LOT of reading. Most of which I don't understand. But what I have read that I can actually remember and out into some form of English language...

Lower the nutrients, the lower the alkalinity you want.

What I read is 0 NO3, PO4...well as low as the test kits we have at our disposal can go...you typically want a dKh under 8.3.

If you have slightly elevated PO4, say 0.05, and NO3 under 5, you want a higher alkalinity of say, 9.5-11.

Or am I missing it?

Right now I tested 0/0, with pH of 8.2 and alkalinity of 9.5...a little elevated from what I have read, but I have battled cyano and won. I battled dinos and I have very much either defeated and/or won that battle, but my levels were somewhat elevated when I started to dose with kalk. Since I have reduced the nutrients, I have stopped dosing kalk.

I guess I am afraid of a side effect of having a raised level of alkalinity (albeit it slightly) in conjunction of my low nutrients.

Many kits cannot read low enough to say that nitrate and phosphate are low enough to be in the possible SPS "burnt tip" zone, which might be equated with a ULNS situation.

That said, it is generally a fine plan to keep alkalinity in the 7-8.5 dKH range if you are concerned about burnt tip problems, or think your nutrients may be very low.

I'd only focus on higher alkalinity if growth rate was the primary goal (or if it is not an SPS tank, in which case I do not think the alk is very important as long as you are in the 7-11 dKH range).

pdiehm · Feb 1, 2016

alkalinity this morning was 8.4. I have 1.5 bags of IORC left, so the plan is to use that up before I think about switching (need to also consider the availability of salts locally).

In a week, the plan is to change 10 gallons. If my theory is right, alkalinity shouldn't go up significantly (120 gallon total system volume). Then it's about figuring out how long should I go without changing water to bring it back up, or look into running Kalkwasser in my ATO.

I'm also probably going to get a carbon reactor, with the pump in my return section and the output of the reactor into the return section. At this time, won't break down the refugium area in my sump as the chaeto continues to grow. I thought about getting the spectrapure dual reactor to run carbon and GFO with 2 different flows, but decided against it at this time since the PO4 readings are 0, and the chaeto is continuing to grow.