This farm had problems with reduced yields and deteriorating water quality. We suggested using AQUA-Cal+ standard protocol to improve water quality and in doing so destressing the shrimp and improving yield.

case study summary

Challenges
  •  Low survival rates
  • Poor water qualitys
Objectives
  • Increase water quality
  • Increase survival rates
  • Increase harvest weight
Solution

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AQUA-Cal+ is a water conditioner, developed by Calix, that safely addresses disease and pollution, delivering improved feed performance and yield.

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Introduction

This customer is involved in a marine shrimp hatchery and grow out farm. Years of discharge of toxic sludge to the waterways in this area has resulted in deterioration of water quality and degradation of the habitat. This has resulted in reduced productivity and susceptibility to disease.

AQUA-Cal+, making aquaculture more sustainable

AQUA-Cal+ has already begun to transform prawn and shrimp farming, as well as fin fish farming. It improves water condition, reduces stress on the animals and helps lead to increased harvest weight and survival rates, whilst protecting the environment.

Multiple benefits in a single solution:

Improved water quality

  • AQUA-Cal+ works as a water and pond bottom conditioner; clarifying the water, controlling pH and releasing alkalinity as required to aid in the digestion of organic matter.

Less stress on prawn and shrimp

  • With stabilised conditions in the pond, stress is reduced. When stress is reduced and water condition is improved, both fish and prawns become healthier and more productive.

Sludge volume reduced

  • As AQUA-Cal+ neutralises the pond bottom sludge and accelerates its breakdown, pond bottom septicity is prevented. AQUA-Cal+ helps release organic material for the growth of phytoplankton (natural food for shrimp), while binding the toxic contaminants. Subsequently, the smell of the sludge is greatly reduced, with less toxic compounds in the water.

Iron suppression

  • Conditioning with AQUA-Cal+ removes the iron by flocculation from the water, significantly reducing turbidity and toxicity. The stocking of the pond after the water is conditioned reduces the subsequent mortality of the post-larvae.

Higher revenue – yield at harvest up to 20%*

  • Results from trials on both Pacific White Shrimp and Tiger Prawns show that AQUA-Cal+ has a superior performance to probiotics in controlling ammonia, nitrite and pond bottom sludge.
  • The data consistently shows AQUA-Cal+ stabilises alkalinity; suppresses extreme changes in pH; provides ingestible essential magnesium and calcium; reduces turbidity, improves light penetration; improves phytoplankton productivity; reduc[1]es toxic metals in the system (copper and zinc); and reduces ammonia and nitrite.

 

Observations

Pond size 4000m2
Depth 1.5 m
Stock density 138 pc/m2
Fully Lined pond, Vannamei

Better Stability pH with AQUA-Cal+

The pond using AQUA-Cal+ has more stable pH and less fluctuations compare with control. This means less stress on the shrimp enabling better survival and healthier animals.

 

 

Alkalinity control with AQUA-Cal+

As we can see in the graph, the pond using AQUA-Cal+, alkalinity is more easy to control at a optimum level. As pond 19 in the middle stage have 2 spike of alkalinity which can potentially bring up to undesirable pH. Also we saw some saving in lime. More stable alkalinity at good levels leads to controlled moulting.

Dissolved Oxygen

Dissolved Oxygen of AQUA-Cal+ pond is quite similar with the control pond. As the daily sludge drainage is usual practice, this may limit the algae to growth in the pond by removing the nutrient source. As a result, we do not see significant difference in dissolve oxygen.

Ammonia suppression using AQUA-Cal+

Ammonia suppression on AQUA-Cal+ pond is more significant with more feed input compare with control due this is due to higher survival rate. Control pond even on low feeding volume, ammonia still increase quite significantly. Proving our Struvite model works very well.

Better growth with AQUA-Cal+

As we can see in the graph, the circle show that AQUA-Cal+ have much better growth than control Iin the early grow out sludge drainage has not occurs as yet. However in the later stage slowdown we see a slow down. The reason for this is AQUA-Cal+ is using the phosphate in the feed in the Struvite reaction that controls ammonia.

As shrimp need both protein and phosphate for shrimp growth which mean shrimp growth is slowed. This can be rectify by dosing of phosphate and stopping or reducing sludge drainage; this will provide a phosphate sink (as in earthen ponds) and allow further reduction in FCR due better algae availability.

Much better survival rate with AQUA-Cal+

As for final survival rate (this figure is provide by customer), pond that use AQUA-Cal+ have increase survival rate around 22%. They even mention that pond use AQUA-Cal+ have more biomass compare with control pond.

Conclusion

This farm, like many in the area, was suffering from poor water quality and reduced yields. This is a recurring pattern throughout Asia and can be traced back to the common practice of sludge discharge directly into waterways.

We can clearly see the benefits of using AQUA-Cal+ in a liner pond, even though our full protocol was not followed.

Survival rate is improved as AQUA-Cal+ cleans up the watertable during pre-treatment. When the post larvae (PL) are introduced, the water quality is improved and stabilised. This removes one of the major stress factors in early culture (poor water quality) which allows better survival rates and ultimately improved yield.

We see enhanced ABW in the early stages of the culture. This drops off once the farmer reverts to the usual drainage pattern. We have advised the farmer to reduce the frequency of drainage allowing sludge to be left in the pond. This provides a source of phosphate to allow the Struvite reaction to continue during the full culture, subsequently allowing the ABW to continue to be better than the standard culture.

During the culture we were able to control pH, alkalinity and ammonia, again reducing stresses and allowing increased survival rate.

Both DOC and FCR were improved.

AQUA-Cal+ is non-toxic, non-corrosive, safe, environmentally friendly and meets many core needs in aquaculture.

AQUA-Cal+ is made by flash calcining a mixture of magnesite and dolomite to produce a unique, very high surface area powder, and then hydrating the powder to produce a slurry for ease of application to ponds. It has been specially formulated to impact on both the aqueous and benthic ecosystems in the pond.

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