Please help w several testing water questions, alk/calcium, vinegar dosing

[padova335i]

I have a 400 g DT w about 550 gallons of true total water volume, 18 fish, 10 pretty large tangs.. So I have been in the process of lowering my alk to at least 8 down from 11 since i dose vinegar and have seen some tips on my sps burning a little..most of my sps look great w great polyp extension and great colors.. Im doing this slowly.. I have several questions that seem a little complicated to research.. Im getting a lot of different info from reefers/internet

How can i get accurate readings of my phos and trates? I have 18 fish and they are constantly pooping.. should i only take water samples from sump area? is this even possible to test right?

is it ok to be dosing different amounts of alk and calcium? i use a bubble magnus and was dosing 200ml alk and 200 calcium daily.. I have slowly gone down to 100 alk a day and actually raised my calcium because its testing at 380.. this seem ok? then when I reach my 8 i will adjust slowly?

water changes? i change 20-40 gallons weekly or every other week.. i use reef crystals and im worried of using it now since its alk is around 11 and mine is getting lower.. can i continue to use this salt or will i end up bleaching out my sps?

Thanks guys... i dont want to screw anything up my tank has been doing well until i started dosing a bit my vinegar and got alk burn from dosing.. btw i dose 40 ml of vinegar a day, going up to 80 is what started burning some sps.. so im lowering alk so i can dose 80 or more depending on trates/phosphates of course..

 

[Timfish]

Personally i wouldn't worry about it the fish pooping and just test the water column. I use the Elos Professional Phosphate as it's very sensitive (I personally do not use Hanna as it can give a false "good" reading when the phosphates may actually be too low).

Here's some research to help understand what your corals are doing with phosphate and nitrates/ammonium and fish poop:

Phosphate uptake: http://jeb.biologists.org/content/214/16/2749.ful

Nitrate uptake: http://www.jstor.org/discover/10.2307/986496?uid=3739656&uid=2&uid=4&uid=3739256&sid=21103122261107

Ammonium uptake: http://www.ingentaconnect.com/content/umrsmas/bullmar/1979/00000029/00000004/art00011

Fish as major carbonate mud producers: http://www.pnas.org/content/108/10/3865

 

[padova335i]

thanks Tim, had to read those a couple times.

what do you others guys think? any comments help..

 

[Timber77]

What are you trying to accomplish by dosing vinegar ? If its to use less 2 part, would be simpler and more cost effective to use a calcium reactor on a tank your size.

 

[padova335i]

What are you trying to accomplish by dosing vinegar ? If its to use less 2 part, would be simpler and more cost effective to use a calcium reactor on a tank your size.

no, its not even that much i was using.. now im using a lot less... its for the reduction of p03 p04.... (lowering alk because i was getting alk burn)

im down to 8.5... my goal is alk of 8... i have lost some small sps colonies by dosing vinegar and burning my corals... so i cut back on the vinegar dosing and soon as my tank and corals look good i'll be back at it.. im also adding more rock to my sump... (cryptic zone)..

switching to red sea reg salt to keep alk more stable in case of big changes.. my tank was doing really well before.. kind of ****ed im making these changes but i think its def better for the long run.

switching to elos nitrate and phos kits.. the hanna is never consistent. idk

 

[padova335i]

ok so im finally at 7.7 alk, 425 calcium.. ill continue to test weekly.. I did notice that one of my chalices receded a bit.. Some of my sps got a little mor alk burn.. everything seems ok now.. I wonder if my tank has to get used to these new levels..

I just ordered 100 lbs of dry rock.. I will be adding it slowly to my new cryptic area.. I also plan to fill up a 75 gallon which is hooked up to my sump area as well.. (holds frags on a rack but will fill a lot of the tank w LR)

I also set the skimmer a tad higher... I will see how this works out for a few months using no gfo....

i will keep an update here... as far as the vinegar goes ive been doing 40 ml a day.. i will gradually go up if needed... I have been feeding slightly less as well.. so a large nori sheet daily split in two meals.. some days some pellets as well..

Its very strange how some of my sps are doing so well and other get alk burn.. if its even alk burn!