Is it feasible to remove the skimmer? Could it solve the decades-long problem of nutrient accumulation?

[Belgian Anthias]

Your point that you need both N and P to grow organic matter is well taken. However, the numbers are not really accurate since if a tank had .25 of water level phosphate, there is a massive amount bound in the aragonite that will get released when you start to lower that water level. In the end, probably more phosphate left over even if you took the N down near zero.

Aragonite as a P reservoir should not be overlooked as an intended consequence of not exporting enough. It can take a massive amount of media down the road to get it out later.

To remove 20ppm nitrate by bacterial growth +- 2 ppm phosphate is needed. If only 0.25 ppm is available this amount includes the P released .. Your opinion aragonite will release the P needed? This means in a 1000l tank a lot of aragonite is needed ( +- 0,2% P).
Using photo-autotrophic growth ( AAM) it depends on the species but the need for P will be a lot less; some bentic algae can take up a huge amount of nitrogen compared to P. That is why we prefer to use a refuge. More nitrogen can be taken up in relation to P at low growth rates, limiting the risk for P starvation. P starvation takes place at very high bacterial growth rates using ammonia, not nitrate. ( bacterial bloom)

If P is released from a substrate due to low availability in the water column, P will always be available. I doubt it will happen just because of having a low level. In the case there will not much aragonite left in systems using GFO.

 

[Randy Holmes-Farley]

To remove 20ppm nitrate by bacterial growth +- 2 ppm phosphate is needed. If only 0.25 ppm is available this amount includes the P released .. Your opinion aragonite will release the P needed? This means in a 1000l tank a lot of aragonite is needed ( +- 0,2% P).
Using photo-autotrophic growth ( AAM) it depends on the species but the need for P will be a lot less; some bentic algae can take up a huge amount of nitrogen compared to P. That is why we prefer to use a refuge. More nitrogen can be taken up in relation to P at low growth rates, limiting the risk for P starvation. P starvation takes place at very high bacterial growth rates using ammonia, not nitrate. ( bacterial bloom)

If P is released from a substrate due to low availability in the water column, P will always be available. I doubt it will happen just because of having a low level. In the case there will not much aragonite left in systems using GFO.

JDA showed that a one pound of dead Florida aragonite rock in a 5-gallon bucket bound 57 ppm of phosphate at less than 0.2 ppm in the water.
.

Phosphate Absorption Rates in Aragonite

The more you add, the more will bind!

www.reef2reef.com

 

[mattdg]

I can't imagine pulling my Lifereef SVS3-24 off our SPS heavy mixed reef. I ran an undersized skimmer previous to that.. Reef Octopus 110 SS. With that said, I'd absolutely consider pulling a skimmer off of an LPS or leather setup, but only after the uglies and fully established. I'd also consider pulling the skimmer if I had an automatic filter roll, but don't like the idea of replacing expensive rolls and tossing them in the landfill when depleted. For me, the skimmer and socks, are the smarter way to go with a tank full of SPS, plus it's cool watching a skimmer do it's thing. When my son was younger, he called it the "garbage man" because it spends all day taking the trash out.

 

[Belgian Anthias]

JDA showed that a one pound of dead Florida aragonite rock in a 5-gallon bucket bound 57 ppm of phosphate at less than 0.2 ppm in the water.
.

Phosphate Absorption Rates in Aragonite

The more you add, the more will bind!

www.reef2reef.com

the capacity of carbon carbonate based media to bind phosphate and sulfate is well known. Once bound it would be interesting to know how much may be released to normal seawater.

 

[Belgian Anthias]

That is why we use a refuge and bio-filter. The calcium carbonate media is easily replaced and cleaned on a regular base. This way removing produced sulfate and phosphate . Till now we did not notice sulfate or and phosphate is released back when the calcium carbonate media is saturated.

 

[Borat]

That is why we use a refuge and bio-filter. The calcium carbonate media is easily replaced and cleaned on a regular base. This way removing produced sulfate and phosphate . Till now we did not notice sulfate or and phosphate is released back when the calcium carbonate media is saturated.

I don't use any filters.. just a fuge and ATS (I am sure I would be ok with just a fuge only). I have to dose nitrates though as their uptake by algae is higher than that of phosphates.

 

[Randy Holmes-Farley]

the capacity of carbon carbonate based media to bind phosphate and sulfate is well known. Once bound it would be interesting to know how much may be released to normal seawater.

All of it is releasable as the phosphate concentration in the water is driven lower and lower. None is released if the phosphate concentration is stable.

 

[Belgian Anthias]

In general macro algae are taking up more nitrogen in relation to phosphorus if the available Nirate/Phosphate ratio is above 10. The general rule 10/1 is for bacterial growth, the vodka method. Also bacteria may be specialized in storing a huge amount of nitrogen or phosphorus for later use. If one wants to remove nitrate using the vodka method all other building materials for growth must sufficiently be available. Bacteria mainly us ammonia-nitrogen, not nitrate nitrogen. Bacteria reacting on free carbon availability with very fast growth all use ammonia -nitrogen. Everything what is growing prefers ammonia-nitrogen as a nitrogen source but because algae can not compete with bacteria for ammonia they use the nitrogen source made available due to bacterial growth,, due to remineralization of which the end product is nitrate, safely stored usable nitrogen.

Because the growth rate using nitrate is much lower, the risk for phosphorus starvation using nitrate-nitrogen is nihil. Phosphorus starvation mainly is caused due to very high growth inflamed by an abnormal situation, for example very high abnormal bacterial growth in the coral holobiont due to free carbon availability.

Depending on the type algae used, a lot of nitrate can be assimilated. Some species whose dry matter contains 0.08% phosphorus and 5.6% nitrogen, other commonly used species contain 0.12% phosphorus and 2.7% nitrogen. ( MB het algenfilter )
To install the growth rate needed one has to feed the algae until the filter reaches the capacity needed. If nutrients have to be retrieved from the water one just has to lead the water true the filter while maintaining the desired growth rate . AAM, active algae management. Most users of an algae filter let starve the algae when nutrient levels go down, growth should be maintained by active feeding. Using an algae filter means harvesting growth, including all elements, which must stay available for maintaining new growth.

Nitrate production in the tank can be managed by correct feeding, managing the protein content of food added. ( supposed there is sufficient filtration capacity available ) No need for supplying only nitrate. Doing so to support algae growth will finally lead to deficiency diseases .
In general nitrogen needed to support macro-algae growth is added in combination with all other elements needed for growth, using one of the many food supplements available for this purpose.

 

[Belgian Anthias]

The question then becomes will the replacement be organic or inorganic?

To clear the water of all nutrients enough balanced growth is needed and growth must be harvested. Space is needed in relation to the bio-load and carying capacity needed. A skimmer will limit the space needed but will prevent balanced growth due to selective removal of nutrients , leaving nutrients as nitrate to accumulate. My opion A skimmer is useful only if the space needed can not be provided . An aquarium system grows, the bioload increases, the needed carying capacity increases. The space needed to support the carrying capacity will increase if the bio-load can not be managed, if growth rates and harvesting growth can not be managed.
Organic growth removes inorganic nutrients, DOC is removed by heterotrophic growth ( remineralization) producing inorganic nutrients. Produced Inorganic nutrients and CO2 are used by photo-autotrophic growth , restoring the balance between reducers and producers. Growth of producers or and reducers is encouraged in a refuge in a way growth can be harvested without disturbing the balance between reducers and producers. AAM, active aquarium management.

 

[Belgian Anthias]

All of it is releasable as the phosphate concentration in the water is driven lower and lower. None is released if the phosphate concentration is stable.

There is 0.2ppm phosphate. A daily measurement shows the level is stable.
Maybe the level is kept stable due to aragonite is releasing phosphorus compensating for consumption or aragonite is taking up produced phosphorus compensating for overproduction. Following the definition none is released if the concentration is stable.
One day the level goes down, due to natural consumption or using GFO. Following the definition the aragonite must be exhausted or the aragonite phosphorus releasing rate can not follow the needs. Anyway, if phosphorus bound to aragonite is released if the concentration goes down, at what point the level is driven down?
Does this mean a system in which aragonite is replaced on a regular base, before saturation, aragonite is able to compensate phosphorus concentration fluctuations and the system becomes self regulating on a chemical base, compensating for a bio-based unbalance?

 

[Randy Holmes-Farley]

There is 0.2ppm phosphate. A daily measurement shows the level is stable.
Maybe the level is kept stable due to aragonite is releasing phosphorus compensating for consumption or aragonite is taking up produced phosphorus compensating for overproduction. Following the definition none is released if the concentration is stable.
One day the level goes down, due to natural consumption or using GFO. Following the definition the aragonite must be exhausted or the aragonite phosphorus releasing rate can not follow the needs. Anyway, if phosphorus bound to aragonite is released if the concentration goes down, at what point the level is driven down?
Does this mean a system in which aragonite is replaced on a regular base, before saturation, aragonite is able to compensate phosphorus concentration fluctuations and the system becomes self regulating on a chemical base, compensating for a bio-based unbalance?

Having exposed calcium carbonate surfaces will tend to buffer (reduce) rises and falls in phosphate since it will bind or release phosphate to help offset the changes (exactly like a pH buffer adding or releasing H+ when pH changes).

Adding phosphate-free aragonite will tend to act as a sink for phosphate until it comes to equilibrium with the phosphate remaining in the water. Likewise, adding aragonite with phosphate on it may tend to act as a source.

There's a thread in the New to Reefing forum where someone washed their new sand in high phosphate tap water, and it is now acting as a source of releasable phosphate when they put that sand in phosphate-free water.