[Crabbit]

I think its more to do with ions changing in their chemical state, so the phosphate that is binded is released. What fluctuations have you had in your KH? I would say that if your bi carbonate have dropped to cause the release but this would have a suppressed reading on your PH as you already know.

[Dave.I]

Im not sure Quigs but i think the ph has to drop pretty darn low to release phosphates.Lower than you had anyway.I will have a dig.

Dave

[Dave.I]

Here you go Quigs.There is a brief mention of bound phosphate leaching at lower ph levels toward the end of the article.
http://reefkeeping.c...9/rhf/index.php

Dave

[Dave.I]

I dont know much about calcium reactors Quigs but it does say that bound phosphate can leach from aragonite etc.If it was me i would be a bit conserned by that reading from the effluent and probably change my media as you say.

Dave

[Dave.I]

Hmmmm.....glad im going onto the balling meathod even more now.Didnt know that Quigs,thanks for posting!

[Dave.I]

10% weekly water change and thats it to take care of chloride.Loads of people say about this but they are adding it with off the shelf calcium/magnesium products just the same.I just look at the euro tanks.They recon that 80% or so use balling and there tanks look awesome! I would rather have a tiny chloride build up that is easily delt with than potential phosphate and ph issues but we will see!

Dave

[Crabbit]

I think that you should try making what is coming out of your reactor stay in contact longer with the rowa, not sure what your using but it sounds as if it has to be bigger. Try soaking the media in RO water and it if thats bad run a phosphate reactor on the bucket your soaking the media in. Phosphate is hard to flush out of a system. Best bet is to bite the bullet and get a large tub of media and change it little an often. Also have you checked for other sources R O unit and i have just had shocking results with my salt lately. I had no phosphates from my RO water and after i mixed my salt in i had a lot of phosphate it is often over looked. With the results i had, doing water changes would make the system worse.

[Dave.I]

Good post Crabbit.It just shows that we should always test our water change water before adding to the aquarium!

On the subject of leaching phosphates...... We are always told corals consume phosphate to grow so if using a naturaly grown product in a calcium reactor like coral branches,coral gravel etc does that mean that it will always leach phosphate due to consuming/absorbing it whilst alive?

Quigs,im just getting my alk,calcium and mag smack on were i want them then i will be off.I will do a full write up on it including pics and dosing info.I will be using fauna marin products with there recipes.I wont be adding the trace eliments for a month or two so that when i do add them i will be able to see if they realy make any difference to colours etc.

Cheers!

This will probably raise a few eyebrows but has anybody ever thought about using cuttlefish bones in a calcium reactor? They are free after all!

[Dave.I]

Cuttlefish bone may well solve the phosphate issues,it could be worse but i dont see why i wouldnt try it,just test regularlyI think youre wright about it dissolving quicker but again that might not be a bad thing.If they dissolve quicker/more easily then maybe that would reduce any ph issues?

[Crabbit]

Apparently soaking helps a little some would be released as the PH of RO should be low.

[lindsay]

Hi m8 ,the sps system sits at a ph of 7.89 to 8 ish with the reactor off line at night but have never seen any rises in phos readings with these ph readings .Not sure but would think that ph would have to get to 6.5 or lower lo let out phosphates in the system and this would probably come from things like a dsb or bottom of sand bed in tank or sump.
If this has happened then perhaps at sometime the ph dropped lower in the main tank than you think and could be because of the high amount of flow at a low ph that you are putting through the reactor .
I have backed are reactor to 45 to 50 ml per minute at a ph of 6.15 and have found the tanks readings are as good as when i was using 100ml at 6.15 .By using a lower flow the tanks ph is a little higher .
I also found that at the high end ie 100ml flow nuisance algae would try to have a go ,its a lot of co2 to use up at a 100ml a minute and keep the ph at around 6.2 in the reactor .

[Simon Garratt]

Hi Quigs.

I spoke to Linds earlyer today and said i'd get on here if i got the chance.

Re the reactor effluant. Most medias give out a proportion of Po4, what people commonly forget is that just like measuring the DkH and the Ca, you are looking at a concentrated level within a small test sample that is going to be dispersed into a hugely different volume. so although a reading of 0.1ppm may seem allot in the concentrated effluant sample, it isnt a representation of the tanks volume... In effect, if you have 0.1ppm in say a 20ml sample, thats going to get diluted to 0.0000000002 in a 1000l system. so no big issue.

Re the GFO after the reactor, i wouldnt bother for two reasons...1 as far as im aware GFO will only bind PO4 down to a Ph of around 7.2, and below 6.8 it starts to dissolute or break down. i may need to check that info but if i reca;ll correctly they are the figures attained on a research paper somwhere. in effect, its actually serving no purpose, and it may be breaking down and making its way into your system as extremely fine dust.


Re the Po4 dissolution:

All systems when new that have a substrate will precipitate a proportion of Po4 into the substrate and possibly rockwork in the early days untill a chemical medium is met where the surface chemistry of the grains, matches that of the surrounding water (just like the white precipitation you get on new pipework or powerheads). if the system goes through a period of elevated Po4 during these days then more is bound. equally even if you are running GFO from day 1, if you have high nitrate, you are probably precipitating surplus PO4 as well as whats being removed by the GFO..This is one of the main reasons i stress to people to stock slowly from day one and let your readings dictate when its safe to add more fish and food...if you let the nutrient pool build up beyond natural levels, not only do you have to deal with the imediate symptoms, you will also have to deal with the consequences later....

remember that initial binding that i mentioned earlyer..

Well, this generally happens initialy through out the entire substrate layer, up untill bacterial colonisation starts seperating the substrate out into layers of 02 saturation (usually around the 7 week mark) at which point you start to see a gradual decrease in Ph in the substrates as you go deeper and more and more 02 is used up. At some point or other the lower layers start to fall into dissolution becouse of the more acidic environment (ive measured pH at (7.2 and lower at 6" deep in my DSB), as this starts, bound Po4 is slowly releaed back into solution whilst additional minor levels of free Po4 are bound in the upper layers at the tanks normal pH values. Now, Be it by critter action or simply ongoing physical disturbance (flow, digging fish etc) upper substrates especially finer ones work their way downwards into this lower pH zone to release what they have bound and you end up with a constant cycle going on with Po4 going in, and Po4 comming out minus that which is consumed by surface dwelling micro algal populations. This process is pretty much unavoidable and a clear indicator of it is that with fine aragonite substrates that are any deeper than about 1", you will find you need to top them up occasionaly. Part of it is what's washed away, the rest is dissolution from the lower layers. Not to any degree it really buffers your systems pH or Alkalinity but certainly to a minor degree.

Now the fun starts when the tank goes through a period of suppressed pH. If the tank drops by a good .1 below its normal lowest nightime pH, then you can bet your bottom doller that within a short time frame your lower substrate pH drops as well, giving rise to a sudden increase in dissolution rate and a subsiquent rapid increase in the amount of Po4 dumped back into the system during that time period. quite often what you see in a test kit can be the result of something thats allready happend, as dissolution into the water column by diffusion is a relatively slow process.

Going back to what i was saying earlyer about why its so important to keep control of exess Po4 and No3 right from day one, Its not hard to see that if you have been lax or not had control of levels at some point, then it will comeback and bite you in the backside later on if the tanks pH goes a bit whacky (over feeding, turning up a calcium reactor too much etc etc)..the worse your levels were during that time of exess nutrients, the larger the pool of bound Po4 waiting to come back out.

as a basic rule of thumb, If you never suffer an No3 and Po4 issue from when you set up the tank, then chances are you dont stand any chance of suffering major Po4 dumps later on even if you do have a short term pH issue. becouse there was never enough surplus there to get bound exessively in the first place beyond normal background levels.

My advice:

Run some GFO and change it regularly for the next month or two to stay on top of whats being released in the background, and get your tank pH up by whatever means, to slow the rate of dissolution that you currently have at your suppressed pH level.

And dont forget that GFO lowers your pH if used in quantities beyond the manufacturers recommended dosage V system volume.


Hope that helps some.

Regards

Si.