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Changing ratios over time?

I have recently seen my water clarity go from pretty good to grim, without increasing my feeding rates or taking away any filtering capacity. What has happened though, is that I started focussing heavily on fruiting crops and I have a sneaky suspicion that the large root mass that I now have in my gravel beds are messing with my component ratios. The system is now a bit over a year old in its current location, and is still extremely productive. I am just thinking that fruiting crops over time deminish gravel bed operation. Any thoughts?

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Permalink Reply by RupertofOZ on March 22, 2011 at 5:25am

Possibly.... what depth are your beds... and what media....

Oh, and what's your pH reading??

Permalink Reply by Kobus Jooste on March 22, 2011 at 5:33am

The beds are 30 cm (12 inch?) and the media is gravel ranging from 13 to 19 mm depending on the beds. The pH was floating around 7 last time I checked, which was around 10 days ago. It tends to come down to 6.5 without any help thus it is now likely between 6.5 and 7. Water quality problems is related to suspended material, which I never had before. A few weeks ago, you could still see the bottom of the fish tank, but now the visibility is down to 10 cm. Fish are still happy, but if I turn a raft bed into a settling tank, there is a rapid build-up of materials, suggesting to me that it is just passing through the beds now and not getting trapped.

Permalink Reply by Rik Kretzinger on March 28, 2011 at 10:37pm

What part of the country do you live in? temps in your local area can effect your bacteria in the grow beds. I have a outside system in Northern California that media temp are around 45 to 50 degrees F and I have a indoor system that is running around 60 to 65 degrees F. The outdoor system is cloudy and is acting just as you describe the indoor system is perfect and water is clear and working fine. Gravel grow beds are all about the bacteria and the populations they support. Gravel is neutral in this equation. If you are seeing diminished results it is not the gravel it is all about the bacteria populations for me. Bacteria have specific temp ranges that they like grow in. Sounds like the pH is about right for your system so it might be a problem with the gravel temperature.

Permalink Reply by Kobus Jooste on March 28, 2011 at 11:40pm

Our temperature ranges are a real problem. The water clarity issue started showing up when temperatures were still relatively stable in the summer band, but we swing from 32 degrees at night in winter, to over 105 in summer. My water temp in summer hovers between 73 and 90, while right not it is between 60 and 70 - the nights are cooling down but the days are still very hot.

I really think that the otside system was starting to show a shift to a pattern where the fines were no longer getting stuck in the gravel, and the plant roots maybe creating "pathes" in the beds for the water in stead of it having access to the whole empty gravel bed before. I see in Dr Lennards calculator text is a recommendation that gravel beds get a quick flush every 6 months to a year. I'm considering doing that as I replace plants in some of the beds just to see if it makes a difference.

I also had some pH issues, but took at least a month to gradually lift it from around 6.4 to where it is now.