Urgent High Nitrates, Corals Deteriorating, RBTA Keeps Splitting!

Hello,

I have a 2.5 feet 19G, it's initially set-up in mid-July as a 5-gallon, but I upgraded it to the current one 4 months ago.



For the past one or two months, some of my corals have been deteriorating - buttons disappearing and rotting, clove polyps greatly reduced to <10 polyps, green star polyps bleaching and shrinking.










THEN


















NOW


That aside, my RBTA (bought in October) has also been splitting like crazy - I have FOUR now, the latest split occured just TODAY.


THEN



NOW

I think it's because of my nitrates, they're high - 40 ppm. I've tried cutting down on feeding, 8-litre water changes (with distilled water) every 2 weeks, nothing's working!

Please help!


PARAMETERS

Temperature: 26 degrees celcius
Ammonia: 0
Nitrite: 0
Nitrate: 40!
Salinity: 1.025
KH: 8
Phosphate: 0.25 - 0.5mg


Tank size: 30" x 12" x 12", 19 gallons

Current inhabitants:
Tomato clownfish x 1
Yellowtail Damselfish x 1
Bicolor Blenny x 1
Six Line Wrasse x 1

Clean up crew:
Top shell snail x 2

Filtration:
Aquaclear 110 (doubles up as refugium)
Purigen (1 sachet)
Sera Phosvec Granulat
Filter Carbon (changed every 2 weeks)

Lighting:
4x24 w T5 HO - 2 x ati aquablue, 1x ati blue plus, 1 x giesemann pure actinic

Feeding:
Fish - Once daily (alternating between pellets, flakes, mysis and brine)
Anemones - Twice a week, 1cm wide cuts (alternating between prawns and squid)

Water change schedule:
8 Litres (2.1 gallons) every 2 weeks.

Salt Brand: Red Sea Pro

Water source: Distilled water

Additives/supplements used: none

 

So you think the splitting could be caused by overfeeding? It's strange though, the last split happened just 3 weeks ago.

But some of my zoanthids are rotting off, and the clove polpys are diminishing by the day! And some zoanthids aren't opening properly too :-/

Could it be a problem with my filtration? All that's in the Aquaclear filter is chaeto and caulerpa, a piece of live rock, a filter sponge, Purigen, carbon and phosphate remover.

My oldest bulbs are around 8 months old, newest ones are 2 months old I think.

 

I had a similar problem about 4 years ago, worked out in the end it was due to my salinity, I was using a hydrometer which was so inaccurate, it read 1.024 but when I eventually compared it to a refractometer my salt water was actually at 1.031. Do you use a refractometer to measure your salinity?

I agree the high nitrate reading could be due to overfeeding, you could also try using a gravel siphon to siphon your sand bed. If you do siphon, only siphon about a quater of the sand bed at a time then leave at least 1-2 weeks before siphoning another 1/4. Doing this once a month helps stop detritus building up and stops cc from binding.

Phil

 

I'm using a refractometer, so it should be accurate right?

I don't think I can siphon my sand bed because the sand is too fine, it'll all just get sucked up. :S

 

Refractometer will be an accurate way of measuring salinity, as long as it kept clean and is occasionally calibrated using RO water.

You can siphon fine sand, I do it in my own tank. You need to use the gravel type cleaner with the large tube connected to the thinner tubing. You just suck up the sand into the large end then when the sand is about 1/2 - 3/4 of the way up the tube raise the gravel siphon out of the sand and the sand will tumble out minus the detritus which gets siphoned out. You will enevitably suck up some sand but its usually only a tiny amount compared to whats in your tank. This has done wonders for my tank. Even with sand sifting stars and snails, plus a sand sifting goby.

 

As nitrates are rise zooxanthellae (sp?) thrives – this is a single celled plants basically you might now them as plankton or phytoplankton. What happens is that these little buggers will compete for inorganic carbon which is used for photosynthesis and also skeletal development. So nitrates can negatively affect your corals that require the uptake of calcium – now, its too early in the morning and I am short on my daily caffeine intake, so I can’t recall how alkalinity plays a part in this (tho someone will have my back) I believe that increasing the alkalinity can offset this occurrence. I have read articles in a few recent magazine that debate this and some studies find the opposite result, all in all I think we tend to agree….lets get the nitrates to zero.

I am sure you know how to. Cut back on feeding if you are over feeding. Use RO/DI, use of a good skimmer to remove DOC’s, check your filtration and media and keep up with the water changes.

I have done the identical procedure as Phil has described above to siphon your sand, it works like a charm. If you suck too much sand up before lifting on the siphon just crimp the hose and it will drop back. If you cause a large cloud of death when the sand drops make sure you do your best to suck it up – you do not want to blanket your tank with that.

It appears that even in your earlier pictures you had diatoms or maybe even cyano on your sandbed – a forewarning for where you are now. The key will be to work on lowing these nitrates and to get the other test kits as recommended above. Ensure you are using a quality salt mix (you do since u use red sea pro). Distilled water use should be changed to RO/DI if possible. Pick up a phosphate remover and increase the water changes from every other week to every week and change out 20%.

 

This is correct, phytoplankton, macro algae and cyanobacteria will all compete for nitrate, phosphate, inorganic carbon and organic carbon. Inorganic carbon in seawater is found as carbonates and bicarbonates (alkalinity) and is in high amounts in seawater. It is difficult to adjust alk to control algal growth because lots of other organisms rely on alk being at correct levels, e.g too high and it can burn corals, too low and corals skeletons will stop growth and start dissolving. You can however limit nitrate and phosphate.

Phosphate in high amounts will bind to calcium and this will prevent coral growth.

Nitrates are poisonous to corals and fish in high amounts. You wouldn't want nitrate to get above 40mg/L.

 

I agree. Whenever I do water changes I always try to get as much detritus out as possible and this works wonders. This includes syringing the bottom of my sump to get fine settled particles, lightly blasting rocks inside and out with turkey baster to disturb detritus for removal and siphoning sand bed in small amounts. Using RO water with a TDS of 0 and a decent salt mix is the best water you can use for a water change.

 

More on this; after phosphate has been bound to calcareous rocks and sustrate, it can then leech back into the water column and cause algal and cyano problems later on.