A friend and colleague passed this post along me. It adds some more perspective to some of the issues of using the pellets
"Just thought id dive on here folks and offer a mix of observations based on research with both medias.
This information is derIved from various sources ive worked with over some time now, some of whom are more than qualified in my opinion to offer reasoning behind the points raised.
Issues commonly encountered:
Excessive clouding of the aquarium and associated risks....(oxygen depletion causing stress in fish, Ph suppression, and bacterial overload of the corals mucus coating)
It appears in some cases that clouding can occur due to bacterial blooms within the main display which are caused by two common factors.
1. An excessive amount of media used initially in the presence of very high free nutrient levels commonly appears to trigger a bacterial bloom on the media that exceeds the skimmers capacity for removal. The excess then ends up being shunted through to the main display where it can (at high levels) use up excessive amounts of oxygen leading to stress in fish, with subsequent drops in Ph..
2. Excessive levels of water-born bacteria can (as well as acting as a food source) also adversely affect some corals that lack the ability to shed this buildup from their surfaces via the mucus coating. Sps corals are very well adapted to such conditions having a higher degree of mucus secreting ability comared to many soft corals. Under high light intensity it may well be the case that some soft corals become so heavily laden with this constant bombardment of bacteria sticking to their surfaces under cloudy conditions that it affects the corals ability to balance out gases produced during photosynthesis leading to bleaching.
Recommendation: The start up dose should be pulled back if you notice excessive clouding at any stage, by removing the media, retaining a smaller amount, and washing and rubbing the remainder under RO to shed and kill off any bacteria before storing it for use later. The higher the initial free nutrient load, the lower the startup dose should be, with approximately 1/2 the recommended minimum dose used in systems with No3 levels between 1-5ppm, and 1/4 of the minimum dose used in systems with No3 above that level. Technically, there is no 'minimum' start up dose beyond that needed to start a slow downward trend in free nutrient levels (if you want to start with 100ml/100gallons, so be it if your sitting at 50ppm N03). As those levels start to fall nearer to the baseline, the dosage can be increased bit by bit to spread the now limited bacterial populations ( nutrient limited) across the larger more affective surface area afforded by the increase in media. (why increase the dose as the levels rise?....well, ill get to that in a minute)
Equally the skimmer must come under the spotlight. The fundamentals of this system rest squarely on the shoulders of the skimmers capacity to remove the bacteria presented to it. If the skimmer is not up to the job (poor quality, poorly designed or simply poorly adjusted) it will have a knock on effect in terms of the ratio of bacteria removed compared to that allowed to pass through to the main system...The main aim is to 'remove' as much bacterial mulm as possible, leaving only traces to make it through to the system as coral food (a poor one at that compared to real zoo-plankton it must be said)...remember it is after all an 'assimilation and export' method not not a conversion method as in nitrification or de-nitrification (although some does occure)....If you are not convinced your skimmer is up to the task, consider an upgrade or place a filter sock on the outlet of the skimmer to catch surplus bacterial mulm. This must however be cleaned once every 7 days without fail to remove these bacteria which will die off after approximately 8 days after exiting the reactor and being deprived of the media as a food source. Once the bacteria die, they release what was previously bound back into solution and the whole process just goes round in a big circle with little if any effect on the free nutrient pool.
The recommended end dose:
As the nutrient pool starts to fall and get nearer natural levels (im not using the words ULNS here ) We are NOT trying to create a nutrient poor desert to the degree that zooxanthallae populations start to die back excessively leading to excessive paling in the corals...what we ARE trying to do, is make way for more food addition in an effort to get closer to the natural environment, where corals and fish can have a much higher degree of daily food availability via the natural pathways of prey capture without building up a surplus nutrient pool.
Corals are supremely adaptable animals because they have the ability to derive nutrients from differing sources and to differing degrees depending on the environment. In nearly all cases we effectively starve our corals in one primary area (that being prey capture) forcing the coral to take advantage of dissolved nutrients and light energy to make up for the deficit. If you take away or lower the background levels of dissolved nutrients to more natural levels you have to make up that deficit in the way of real food for the corals to capture and consume without which the coral lacks the energy and nutrients required to produce protective pigments, mucus coatings, and to fuel further growth. so the aim is to gradually increase feeding as the nutrient levels fall. The recommended surplus volume of media above that required to instigate the initial fall in levels is based on the volume required to offer suitable surface area for future populations that have to keep up with the increased food input and subsequent nutrient input after nitrification and to a degree new higher levels of Po4 input. This is where some medias are deffinately better than others....you cant beat surface area at the end of the day when it comes to a bacterial growth platform...the smaller the media, the more surface area available per liter of media used...
In short....as your free No3/Po4 levels start to fall, gradually increase your feeding so the corals are able to adapt to the shift in nutrient pathways...If you don't, your corals will suffer.....And don't be surprised at how much food you can end up putting in once the system has stabilised and your at your maximum dosage for the system volume. from personal experience the amount can far exceed other methods without the drawbacks of nutrient buildup, but you have to take your time and let the system adjust.
NB: In new systems or those that are already at natural trace levels of No3/Po4 there is no reason why you cant start with a higher or full dose, becouse any bacteria present will already be nutrient limited, so blooms are far less likely.
Time as an indicator of success:
Basically, if your seeing a fall from 50ppm No3 in just a couple of weeks to 5ppm or less its NOT a good thing in reality because your corals wont have time to adapt to the shift in nutrient pathways. What you really want to be looking at is a fall over several months to give both your corals 'and you' a Chance to shift the pathways over. you cannot hope to get a handle on how much to increase feeding by if your levels are falling like a stone because by the time they hit natural levels (sub 0.1ppm NO3 and sub 0.008ppm Po4) which is the point the bacterial populations will become nutrient limited to the degree full deprivation becomes virtually negligible. you wont have had time to gauge if your corals are getting enough food or if they are still falling into energy deprivation. So the main aim is to keep the process as a slow adjustment for both you and your corals.
Bleaching in soft corals and some LPS may also be linked to another factor:
Its been reported on many occasions that an increase in water clarity is encountered as the bacterial mulm acts as a flocculant, binding other material in the process and clayfying the water (not to be confused with carbon). This increase in clarity can cause stress in some soft corals which lack the ability that many SPS have to rapidly produce protective pigments in an effort to combat changes in photo saturation. It may well be the case that increased clarity has simply led to these corals becoming stressed via over saturation or increased UV penetration.
As for claims regarding possible contaminants I can verify that 'NONE' of the bio media brands on the market in the UK at present contain anything that can be of harm to livestock, be that SPS/LPS/or otherwise. There does however seem to be some situations where certain corals have reacted adversely, but there certainly isn't any 'trend' beyond those attributable to the fact that some corals in some situations may suffer stress if the tank conditions are altered drastically within too shorter time frame or adequate measures are not taken on the part of the keeper to make up for the shift in nutrient pathways leaving the coral weak and susceptible to infection or other factors as previously mentioned such as bacterial fouling. Some corals simply dont like being subjected to change which is a game we all play.
Po4 uptake the truth:
For the process to work effectively you need both nitrate and phosphate availability. If one or the other reaches natural levels, it then becomes the limiting factor for the 'whole' process. So its not surprising that some report Po4 or No3 sitting stubbornly in the absence of the other, in which case secondary measures are required, IE water changes in the case of an No3 pool, or Po4 removers in the case of a Po4 pool. In reality, Po4 addition/generation is far higher than NO3 generation in closed systems due to food input, so it will inevitably lead to an imbalance of availability, with No3 usually being the limiting factor, and a surplus Po4 pool to be taken care of. In essence don't remove your Po4 reactors, because it will still be required to take up that surplus input beyond that being assimilated with the available No3 pool...what this process will do is make your Po4 remover last allot longer though. (as the blurb says 'reduces' Po4 and No3')...nobody ever said it does it in perfect balance.
Hopefully this will answer a few questions, but if i can be of any further help then please feel free to ask and i'll offer what input i can when i have time.
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Simon Garratt. o.c.r.d"
or maybe add gfo, back into the system.
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