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mistakes r crucial
Thu Nov 09, 2006, 09:11 PM
Hi all,

For a long time we've had a degassing chamber on our wish list but with the amount of water we run the cost of a commercial unit (up around $3000 per unit) has always put it on the back burner. We decided to have a go at making them ourselves and we're pretty happy with the end result. Thought I would post them up here as someone might have a few ideas on how we can improve them. They cost us less than $300 each so a huge saving.

The sump is 400 litres in the grow out and it has 5 trays of different media with the return sat on the top tray. There are 5 bins above the return with a spinning arm in the top one which pushes water through an 800 micron filter sock, dacron and Japanese matting (course green stuff). We've used trawler net in two of the bins for media and gutter guard and bio balls in the others. Drilling 300 small holes in 9 bins was great fun, not! 2700 holes later I never want to see a drill bit again.

As we have a flow issue with our grow out system (29,000 litre an hour pump and it still won't pump water real well to the third tier) we've plumbed a 10,000 litre an hour pump into the sump so the water returns from the system, down through the 5 trays of media and the new pump then takes the water from the sump up to the spinning arm and back down through the tower.

The tower on the breeding system is almost identical but because we don't have any pressure issues we've split the plumbing from the sump and taken half the water back up to the tower and down again, if that makes sense. If anyone can suggest any improvements we'd love to hear them.
Cheers
MAC

endless
Sun Nov 12, 2006, 07:42 AM
umm this might be a stupid question, but... wot is it suppose to do?

samir
Sun Nov 12, 2006, 08:02 AM
another silly question. why don't you use different pumps for each tier ?

mistakes r crucial
Sun Nov 12, 2006, 08:08 AM
Hi Endless,

I didn't know anything about them or what they were either until a few months ago but a friend of a friend (filtration guru) recommended we use them because of the amount of fry/juveniles we have in our system.

When you run a closed recirculation (sump) system as we do you can get a build up of carbon dioxide in the water which is not real good. Carbon Dioxide build up can create large fluctuations in Ph levels with obvious consequences, instability, which leads to stressed fish which equals health problems and no growth.

Because the water is pushed out through a spinning arm and trickling down through so much media it gathers heaps of oxygen which has got to be beneficial. It's also provides much more biological filtration because of all the media the water is running through in the tubs. Putting the water through two lots of filtration also ensures the vast majority of solids are taken out of the water.

I hope that makes sense, I'm no filtration expert but that's how he explained it to me in simple terms.
Cheers
MAC

mistakes r crucial
Sun Nov 12, 2006, 08:15 AM
Hi Samir,

We thought of that one and it aint a stupid question but we came to the conclusion that we would get back pressure problems which is even worse than the issue we have. We've got it working but the flow in the one tank on the top tier is not where we really want it. It'll do for now until we move next year, we just keep the stock levels in that tank to a minimum. Also, if you saw our electricity bill the last thing you'd suggest is another bloody pump lol!
MAC

Dkarc
Mon Nov 13, 2006, 04:01 AM
Try putting a control valve at the beginning of each tier. Cut back the flow on the first tier and the excess water will flow to the top tier....keep adjusting the valves until you have equal flow on each tier.

-Ryan

mistakes r crucial
Tue Nov 14, 2006, 07:44 AM
Hi Ryan,

Every tank has a control valve on it and we have a much slower rate on the bottom tier than we do on the top. It's working OK now, not perfect but its doing the job.

By the way, hows that food trial going.
MAC