+ Reply to Thread
Results 1 to 5 of 5

Thread: Phosphates

  1. #1

    Join Date
    Jan 2011
    Location
    UK
    Posts
    137

    Phosphates

    http://www.skepticalaquarist.com/phosphate-cycle

    This is a link to a really good article on phosphates. To anyone like me who finds the whole subject hard to grasp sometimes it gives a good insight into the processes happening. Yes I know it is focused on freshwater but the principles are the same.
    It might explain why people get varying readings for phosphate levels from one day\week to the next and why some people with zero readings have nuisance algae and others with readings have no algae!
    The most interesting bit for me was towards the end with regards to cyanobacteria. It appears they can produce an enzyme called phosphatase in large quantities. This enzyme enables it to convert any phosphates bound up in organic matter, ie detritus, into a form it can use for its own needs. Phosphatase is relatively energy expensive so is only usually produced as a necessity during periods when phosphate is limited. Could explain why people who dose organic carbon sometimes get blooms of cyano, maybe the extremely low dissolved levels of phosphate encourage this phosphatase production.
    Also may be a good reason to remove as much detritus as one can regularly to stop the cycle before it starts. Unlike the nitrogen cycle the phosphate cycle on a natural scale takes millions of years. The only way to help is export via your algae harvests and good husbandry.

  2. #2
    Super Moderator
    Join Date
    Oct 2008
    Location
    Santa Monica, CA, USA
    Posts
    9,715
    Really well written. It's the P-flux that I was talking about...

    "But natural reactions are constantly pulling phosphate from the water. For example, iron is quickly oxidized in oxygen-rich waters, and the resulting positively-charged iron hydroxides scavenge phosphate from the water, bind it, and carry it as a component of ferric precipitates, which form on the substrate. In a moment I'll note how this reaction can be harnessed to reduce phosphate in the water. In highly buffered alkaline waters, however, phosphates tend to bind directly to calcium instead. So, with one kind of mineral partner or another, phosphates are continually being extracted from the water and buried in the substrate— as long as the substrate contains some colloidal clay and flocs of humus, or some suitable iron or calcium compounds."

    "Anoxic conditions inhibit the production and activity of phosphatase: thus the anoxic layers of an unplanted substrate can become a phosphate sump. Whenever local levels of orthophosphate drop low, bacterial communities in the biofilm draw on phosphate bound in the sediment: in response to low availability of free inorganic PO4, synthesis of phosphatase will switch on within 24 hours or less."

    "The less orthophosphate is available, the more necessary local recycling becomes, and the more freely phosphatase is produced. So a kind of stabilizing feedback system is established, which is characteristic of aquatic systems as a whole."

  3. #3
    kotlec's Avatar
    Join Date
    Nov 2010
    Location
    Lithuania
    Posts
    710
    Good read . Thanks

  4. #4

    Join Date
    Sep 2015
    Location
    India
    Posts
    3

    Phosphate dosing

    It is really a good one to read. I am a freshwater hobbyst running with algae scrubber. But sometime I fill that growth of green algae is reduced for want of phosphate. But after water changing it goes back to normal. May be phosphate supplied from tap water. Otherwise how to maintain?

  5. #5
    Super Moderator
    Join Date
    Oct 2008
    Location
    Santa Monica, CA, USA
    Posts
    9,715
    You need to check your tap water for phosphate.

+ Reply to Thread

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts