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650 gal plywood tank build

The MFK's DIY section! Enjoy with a PBR ASAP.

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Post Thu Feb 25, 2021 8:54 pm
Pioneer Level 1 Member
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Posts: 9
Trying to do a couple of photo's for you. It's all oak lumber and plywood but I cant upload any pics. Help. Chris

Post Thu Feb 25, 2021 9:25 pm
willie Level 9 Member
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Posts: 1761
Location: Minneapolis
The pictures have to be reduced in size. I believe the maximum size is 100kb, but not exactly sure. Then, use the Upload Attachment tab to upload. If you PM me, I can upload for you.

Post Sat Feb 27, 2021 12:14 am
willie Level 9 Member
Level 9 Member

Posts: 1761
Location: Minneapolis
Posting for Chris.

tank #3a.jpg
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tank #3a.jpg (43.78 KiB) Viewed 577 times


Tank # 4a.jpg
#4


Tank #5a.jpg
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Tank #6a.jpg
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Post Sat Feb 27, 2021 5:06 am
Pioneer Level 1 Member
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Posts: 9
Thanks Willie, when this Covid thing settles down I will repay you with a cold one.

Here we go, base is 2x8 green treat, 2x4 every 12" with double 2x6 plate and rim with a center 2x4 "wall" and 4x8 3/4" douglas fur plywood on top screwed and glue every 6"s. Dead level, DEAD level. Got to start with a good base. Epoxy cote it and it should last along time.

The tank: 90x48x38 tall. I have seen 3 main ways to build a plywood tank that look like they stand the test of time and when tore down look like they are in great shape. There are other ways that work it's just I had to narrow it down and be able to sleep at night. Double 3/4" walls, single sheet with vertical bracing like house wall, or horizontal bracing like they use in aquaculture fiberglass tanks. Building a plywood tank sounds a little nuts but they are strong and have shown they can last. I did not skimp any where. I used all A/high B grade oak plywood with oak core, glued with waterproof Tite Bond 3 and used 2 1/2" coated screws 3" on center with a pilot hole. The front is 4x4 oak timbers from Menards BUT whats great is they are 5 layer Oak hardwood laminate with the grain on edge so they don't twist. They are glued and screwed in from all sides and bottom/top. That's what hold the glass in. Gives me a 2 1/2" lip for RTV 108 on Low iron glass. The ribs, Oak 2x4's, provide all your strength on something this tall and long and should be included on all builds IMO. They are glued on, screwed in every 4" from the inside, lag screwed the corners (not on pic) and holes filled with wood epoxy filler. Seems are Oak coving glued and toe nailed in place for the fiberglassing layers to come so they can make the transition. The top euro bracing I did with 1x4 Oak with 1x2 Oak on top. Very strong. I tried 2 sheets of oak Plywood cut out but it was flimsy. That's not what I expected, so I went with Oak screwed together. This thing is a tank! It's heavy and I cant make it flex and I am a big dude. I will fiberglass corners/inside using epoxy and fiberglass 1208 Biaxial. A chop strand/stitched woven mat combo. I will talk the good and bad along the way. This is not a budget build at all. I have $1500 in supplies so far but it's tough as nails. If you want to do one fire away with questions. Truthfully it's all up to the fiberglassing/water proofing now. Take your time and do it right. This project is a blast!

Post Sat Feb 27, 2021 11:19 am
Pioneer Level 1 Member
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Posts: 9
Made a mistake when doing the Oak coving. Oak coving has a 3/32" lip, the coving doesn't go all the way to the edge and I found out why. I trimmed that 3/32" off and glue and finished nailed it in thinking the glue would hold it flush and it would be perfect. Wrong. It curled. I will be cutting back a 1/16" with an utility knife and sanding it with 60 grit with the palm sander. It totally smooth's it out and makes it perfect but if you ever cut it down on the table saw leave a strong 1/32" edge so it's square and just touch it later. I have a lot of work to do.

Post Wed Mar 03, 2021 10:30 am
Pioneer Level 1 Member
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Posts: 9
Cove sanded and inspected. Looks great with a nice smooth transition. Measure and order fiberglass today.

Post Wed Mar 03, 2021 11:43 am
twinsfan Level 3 Member
Level 3 Member

Posts: 80
Wow! This thing looks beautiful as it is already. Looking forward to following this build. I'm also looking forward to the filtration.

Post Wed Mar 03, 2021 1:45 pm
Pioneer Level 1 Member
Level 1 Member

Posts: 9
I got square poly tanks, UV, and a Red Dragon DC style pump planned. I will show pics. You should see the rock. It's a weathered grey limestone type I have had outside for a few years. I love the look. I will show pics as I go along. The job that is the most intense is coming up. Fiberglass next..................


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