Low DKH usage with corals?

[Floyd-]

Trying to see my usage and from what I can tell im using about .1 dkh a day. That seems super low for having a mixed reef tank. I try to keep at 9dkh and with dosing I was down to maybe 4-6ml a day in my 175 gallon tank.
I have LPS and SPS mainly and a few softies also. I figured they would be using up more alk and cal but they barely touch it. Is it because my PH is lower? I can only get PH up to 8 on a good day.

 

[Spare time]

If the corals are small or few, this wouldn't surprise me given the size of the tank.

 

[Jekyl]

How are your other parameters? How is growth?

 

[Floyd-]

If the corals are small or few, this wouldn't surprise me given the size of the tank.

Its not a whole lot given the size of the tank but its a few dozen. I just figured they would use more is all.

How are your other parameters? How is growth?

Other parameters are such:

temp-78f
salinity-34.5sg
cal-420
mag-1380
alk-9
nitrate-3-6ppm
phos-.15 but have been dropping with GFO in reactor.
PH-7.6 - 8

Growth is super low for most of the corals. Some ive had for a year and I cannot see any noticeable growth other than normal "growers" like GSP and Monti.

 

[Jekyl]

Its not a whole lot given the size of the tank but its a few dozen. I just figured they would use more is all.

Other parameters are such:

temp-78f
salinity-34.5sg
cal-420
mag-1380
alk-9
nitrate-3-6ppm
phos-.15 but have been dropping with GFO in reactor.
PH-7.6 - 8

Growth is super low for most of the corals. Some ive had for a year and I cannot see any noticeable growth other than normal "growers" like GSP and Monti.

Lighting? Seems like everything else is on par.

 

[Spare time]

Its not a whole lot given the size of the tank but its a few dozen. I just figured they would use more is all.

Other parameters are such:

temp-78f
salinity-34.5sg
cal-420
mag-1380
alk-9
nitrate-3-6ppm
phos-.15 but have been dropping with GFO in reactor.
PH-7.6 - 8

Growth is super low for most of the corals. Some ive had for a year and I cannot see any noticeable growth other than normal "growers" like GSP and Monti.

Which corals are growing slowly? Any idea of the relative par values and spectrum the corals are receiving?

 

[Floyd-]

Lighting? Seems like everything else is on par.

Which corals are growing slowly? Any idea of the relative par values and spectrum the corals are receiving?

PAR is fine. I have reefbreeder lights with the "BRS" spectrum running the blues at 70% (100%-50%-10% ratio for blue, white and red, green) Last I measured it was maybe 150PAR in the sand and 300 near the top.

Slow growers are Acan, Paly Grand, blasto. My frogspawn, hammer and torch are all the same size they were a year ago.

 

[Floyd-]

Also tossed in a pic of the tank maybe a week or two ago. I figured all these coral would use more than .1 dkh a day.

 

[Spare time]

PAR is fine. I have reefbreeder lights with the "BRS" spectrum running the blues at 70% (100%-50%-10% ratio for blue, white and red, green) Last I measured it was maybe 150PAR in the sand and 300 near the top.

Slow growers are Acan, Paly Grand, blasto. My frogspawn, hammer and torch are all the same size they were a year ago.

I was more concerned that maybe they are getting too much light. If a tank receives lots of blue light (compared to a much more spread out spectrum), the actual recommended par value may be lower. In my tank, my euphyllia was incredibly slow growing, until I realized they were getting way too much light.

 

[Spare time]

Also tossed in a pic of the tank maybe a week or two ago. I figured all these coral would use more than .1 dkh a day.

Consider raising the light higher up (to the highest the railing allows) This would give better spread.

 

[Floyd-]

Consider raising the light higher up (to the highest the railing allows) This would give better spread.

Doesnt look like it in the picture but its already at the BRS recommended height of 16" for these lights.
What PAR should I aim for? I can borrow the PAR meter again and adjust.

 

[Jekyl]

Doesnt look like it in the picture but its already at the BRS recommended height of 16" for these lights.
What PAR should I aim for? I can borrow the PAR meter again and adjust.

Any adjustments make slowly. 5% reduction every 2 or 3 weeks and note the changes. Pics help so you can really see minor growth details over the weeks.

 

[Floyd-]

Whats the average PAR I should be shooting for for a mixed tank?

 

[Viking_Reefing]

Also tossed in a pic of the tank maybe a week or two ago. I figured all these coral would use more than .1 dkh a day.

Well you consumption is perhaps on the low side but there hardly any corals in there so I wouldn’t expect any large uptake. Honestly, which that coral mass you could probably get away with water changes.

 

[ninjamyst]

Are you feeding your corals? Unless your corals are bleaching, I doubt it's a too much light issue. I have my frogspawn high up on my tank under a Radion at 100% and it grows new heads every couple of months. I do feed heavily

 

[Floyd-]

Are you feeding your corals? Unless your corals are bleaching, I doubt it's a too much light issue. I have my frogspawn high up on my tank under a Radion at 100% and it grows new heads every couple of months. I do feed heavily

Not directly feeding. When I feed the fish I have all the pumps still on and the tank looks like a blizzard with stuff going everywhere. My poor frogspawn has had the same 2 heads for over a year! My duncans on the other hand are growing like crazy.

 

[Randy Holmes-Farley Verified Community Expert]

Lower pH and lower alk reduce alk demand, as does lack of strong coralline growth.

Water changes and additions of alk without knowing it can also reduce apparent demand.

 

[Floyd-]

Lower pH and lower alk reduce alk demand, as does lack of strong coralline growth.

Water changes and additions of alk without knowing it can also reduce apparent demand.

Would it be better for me to run a higher alk (11dkh) to match my PH being around 7.6 - 8.0 to help promote growth?
Not sure how accurate it is but the redsea recipe for a mixed reef has the alk at 11.5dkh.

I try not to do too many water changes becuase of the size of the tank. Maybe once a month at best.