New Project with Fiberglass Tub

frankielynnsie(7B)June 6, 2014

I need any information you can give me. I got a fiberglass hot tub spa blank today to use for a pond. It is a 6 foot by 11.5 foot oval, 3 feet deep. It doesn't have seats or holes for hoses. The sides are 'ribbed' and slope to the middle with just a little flat surface in the center. The outside is rough 'prickly' to the skin fiberglass. The inside is a flat mostly blue color, smooth, not shiny or slippery. I want to use it above ground. I will post pictures tomorrow. Here is where I need help--

1. The lip has a ragged 4 inch thin fiberglass edging that is cracked in places and I want to get rid of this. It is from the making of the tub. What is the best way to remove it?

2. Is there a paint I can spray on the outside that will make the fiberglass not stick into the skin? Do I have to sand off the fibers first? (I would just rather coat them with paint.)

3. If I use it above ground do I need to make a 2 x4 support for it?

4. If I wanted to spray paint the inside, what kind of paint? I don't want it to be slippery because my Granddaughter wants to have it for her personal swimming pool this summer.

I have tried looking it up on google to get an idea of if it needs support, what kind of paint. Some say automotive paint will work.

Anyone with experience with this, any help would be appreciated.

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Holly_ON(6a Ontario)

Would you consider digging it half into the ground? I have done this and it does make it more visually appealing and easier to landscape around it. This would give you the opportunity to do a nice waterfall feature instead of just using a spitter for water movement. To me, a pond this size would be much enhanced by a waterfall.

Personally, I'd forget the idea of using it as a child's swimming pool and make it into a true pond. I've built ponds above ground using preforms supported by earth and retaining wall pavers with fairly good results by planting around the preformed liner. The sedums overhang and hide the pavers nicely. My best rigid pond results came though by half digging it in.

Personally, I'd use a black pond liner instead of paint even though the pond is now sealed. I'd worry about paint peeling over time. Alternatively, if you just leave it a blue colour (depending on the shade), by the time the inevitable algae forms on it, it will not be so glaring. At least it is not red!

Now I've graduated to a proper in ground pond but my first endeavours created an addiction.

I can't stress enough.... no matter how you do it - make sure that it is perfectly level. You will not be happy with it otherwise.

Here is a site on google that I really liked the result of:

    Bookmark   June 7, 2014 at 12:30AM
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waterbug_guy(Phoenix AZ (Melrose))

1. I'd use a grinder, respirator and face shield. Want to be sure what you're cutting isn't needed for structure.

2. Any exterior paint. I wouldn't sand off any because it's needed for strength. Lot's of coats of latex should coat it OK.

3. Support is normally defined by the manufacturer. These things are designed and built to be installed a specific way and each can be different I assume.

4. Painting the inside I don't know what kind of paint. I assume you'd have to sand the gel coat first. But each paint manufacturer will have directions.

    Bookmark   June 7, 2014 at 1:42AM
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It looks like a sow's ear at the moment and I have been cleaning the dirt and plants out of the crevices and scraping off the lichen. Some of the fiberglass on the edges has come off easily but other areas are on better. It is just 1 layer and isn't suppose to be there. I can see a silk purse in the making. My husband can't but he is just going along with me. He said after I get it cleaned up I can put it back on Craig's list and get my $80 back. Don't hold your breath! I have got a place picked out for it and am going to bury it part way. I would love to use those landscaping blocks around it for a place to sit along the edge.

    Bookmark   June 7, 2014 at 12:55PM
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Close up of area that needs to have fiberglass off. Some is totally off in places.

Waterbug guy--I don't have a grinder. Is there a dremmel something that would work???

    Bookmark   June 7, 2014 at 12:59PM
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Areas that need more work.

    Bookmark   June 7, 2014 at 1:02PM
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steiconi(12a-Big Island, HI)

What a cool project! I want one!

A dremel would be way too small, and take forever. Grinders aren't terribly expensive, and may be on sale for fathers' day right now. Get cutting blades, not grinding blades.

Another option would be to get fiberglass and resin and slap a coat on whatever you don't like. It should cover pointy stuff, soften sharp edges, and reinforce all at the same time. I haven't done this, suspect it's messy and stinky. Get supplies at a good auto shop and they can probably give you advice on using it. They can also advise on paint, but I would guess they'd say automotive!

    Bookmark   June 7, 2014 at 1:26PM
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Holly_ON(6a Ontario)

What a find! I'm not sure that you really need to do much with the rough edges once it is turned because you are going to bury it partially. First thing I'd do is test it to make sure it is holding water. Then you will know how to proceed and what if any spot needs reinforcement. I wouldn't worry about the rough edges as you could use the earth you dug out of the hole to mound up to the edge to cover the underside. Random flagstone or large river rocks could be used to cover the edge or just plants will grow over it quickly. I would landscape with plants and mulch to cover the mound.

Any idea of the age of this tub? I would still be tempted to invest in a EPDM 45 ml pond liner which will last for years/decades. it will cover any holes or weak spots that might show up. If you are still worried about rough spots around the lip, carpet scraps will protect the liner. If finances are an issue, well washed roofing liner can be used. This pond will be a lot of work and you want your effort to last. If you have the $$$ to put in a proper waterfall, I would look into an external pump and filter.

If you keep the rim on tub, be on the lookout for plant basket holders that fit over railings. The size looks about the same. I have seen them used to put in the water to provide the right height for marginal plants.

Probably the biggest bargain here is the tub form but don't get discouraged. You have the start of something really unique. It will take some creativity and work. It will not be a weekend project. My first puddle twenty years ago was a twenty dollar garage sale find. Form, pump and spitter included! The retaining wall to build it above ground ten times that! That year my ten cent feeder gold fish got treated to a two hundred dollar rubbermaid stock tank for their winter home! I've since invested over ten thousand into this hobby but the enjoyment is priceless.

Please let us see your pond development as this project progresses.

    Bookmark   June 7, 2014 at 3:21PM
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waterbug_guy(Phoenix AZ (Melrose))

A dremel would work but is slow. Not sure how much you want to remove.

Now that I see pictures it looks like maybe the 2 flat bottoms on the ends are made to rest on a concrete pad. You can tell by looking to see if those bottoms are discolored, if they look like they've been sitting on something. Maybe not.

However the middle part definitely is meant to not sit on the ground and instead is designed to be supported by the edge, the part you're wanting to cut off. So this is designed to be hung from a frame. It can be partly below ground, but at least that middle section (with the ribs) isn't meant to touch the ground at all.

Without the support frame the risk of it cracking open is real. When supported from a frame stress is transferred down those ribs and the biggest stress is at the bottom of the ribs pulling outward, pulling the sides away from each other at the bottom. That pulling stress is what fiberglass is good at resisting. The ribs are the strength. When set on the ground the stress is transferred in the opposite direction, from the bottom of the ribs up to the side tops where the sides will want to bow out and there isn't much there to stop that. Fiberglass doesn't like to bow too much.

The horizontal lip at the top will be under a lot of stress. And if I remember you said there were cracks there? If so it makes sense that the previous frame probably rotted away which caused the sides to bow and crack.

You could string something across the top to hold the ribs together if you don't want to build a frame. You could string steel cable across to connect each rib. Or a piece of 2x4 with a cleat to stop the sides from bowing out.

I would not cut any of the edges off just because that's going to be the stress point unless hung from a frame.

These things are engineered for a specific install and when you do something different it's hard to say how they will react.

    Bookmark   June 7, 2014 at 8:26PM
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Holly_ON(6a Ontario)

Waterbug guy, You have a good point. I don't know if Frankielynn lives in an area where the ground is prone to freezing. Your answer brought back memories of a 300 gallon rectangular flat bottom new fiberglass pond I put in once. It did not crack but the whole thing lifted a few inches out of the ground and affected my waterfall over the winter. I imagine that freeze/thaw cycles could affect the integrity of the shell especially as it appears older.

I'm out of my depth here but could it be stabilized by digging a slightly bigger hole and filling the space around the form with concrete to hold it in position?

    Bookmark   June 7, 2014 at 9:13PM
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So if I understand right the lip and two flat ends need to bear the weight of the water. If I put it in the ground 1/2 way and have the lip resting on landscaping blocks--would this be enough to keep it from pulling apart?

There are no cracks anywhere on the tub. Just the excess fiberglass that is under the lip and partially attached to the sides. It is only 1 layer of fiber and is tearing off with the pliers. I have to get it off so the lip will not be obstructed.

I can support the flat sections on 18" pavers and then pour sand into the void between the flat parts. Is this a good fix? I don't want it to break.

    Bookmark   June 7, 2014 at 9:51PM
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Holly_ON(6a Ontario)

Would it help to tie a steel cable around the pavers to keep them from shifting out?

    Bookmark   June 7, 2014 at 11:09PM
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waterbug_guy(Phoenix AZ (Melrose))

It's impossible to tell what would work and what wouldn't except to say it was designed to be mounted one way, it was engineered to be used that way. All other ways are unknowns. If you can take some closeup pics of the edge, the mounting brackets (those rectangle things at the top of each rib) and the cracks maybe I can suggest something.

In general this type of fiberglass structure doesn't like to flex too much. We like to think soil and sand will provide support, but it moves a lot. In construction loose soil and sand aren't really considered structural. Like I said though it's not possible to predict if it would crack open or not or when. That's the fun of re-purposing material. You try and see what happens.

    Bookmark   June 8, 2014 at 4:02PM
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