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Thread: Did low calcium cause my fiberglass steps to blister?

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    Did low calcium cause my fiberglass steps to blister?

    Split from this thread. Lets keep it all together. Bama

    So I'm picking a late model thread to re-open here with a quick question about a vinyl pool with fiberglass entry steps - I'm noticing dime size blisters on the fiberglass steps. I've been trolling through past threads here and all seem to say CH is not a concern in vinyl liner pools - any chance low CH can cause blistering in fiberglass steps ?

    Thanks in advance !

    Dave
    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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    Richard320's Avatar
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    Re: How to add calcium chloride to a vinyl pool?

    Quote Originally Posted by bumpy1
    So I'm picking a late model thread to re-open here with a quick question about a vinyl pool with fiberglass entry steps - I'm noticing dime size blisters on the fiberglass steps. I've been trolling through past threads here and all seem to say CH is not a concern in vinyl liner pools - any chance low CH can cause blistering in fiberglass steps ?

    Thanks in advance !

    Dave
    Yes, if the fiberglass filler has calcium in it.
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    Re: How to add calcium chloride to a vinyl pool?

    [attachment=0:28ou4u7s]ImageUploadedByTapatalk1373415389.034875.jpg[/attachment:28ou4u7s]

    Thanks Richard. Just got home and snapped this pic. Does this look like the affect of low calcium say 80 ppm ?

    Anything I can do about the black spots ?

    Other than raising C! I'm looking for some opins on a course of action for the steps.

    Thanks.

    Dave
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    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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    Re: How to add calcium chloride to a vinyl pool?

    Just giving myself a bump ... any takers on the questions above ?
    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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    Vinyl IGP with fiberglass steps - blistering, stains, CH 90

    Ok, I resurrected an other thread in another forum and didn't get but one hit. I'm looking for some direction in terms of what to do.

    I have 4 year old vinyl liner IGP with fiberglass steps. CH is at 90. Other test results as follows (been running this way for a couple of years now):
    PH 7.6
    FC 4.5
    CC 0
    TC 4.5
    CH 90
    TA 80
    CYA 35
    Temp 92
    Salt 3,000ppm

    I noticed some blistering on the fiberglass steps last season but didn't make much of it. This season (3 months in) it appears worse and there are black spots accompanying them. Richard (the only responder in the resurrected thread) - confirmed for me that low CH in a vinyl liner pool could cause blistering on FG steps.

    Raising the CH aside, is there anything to be done about the staining and or blisters (pic below) ? Will a CH of 90 cause blisters ?

    Thanks in advance.

    Dave
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    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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    bobodaclown's Avatar
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    Re: How to add calcium chloride to a vinyl pool?

    Try rubbing with a chlorine puck, see if it goes away. It could be algae. It might take some scrubbing. Have you tried brushing them with a high chlorine level.
    Try rubbing with a vitamin C tablet, see if it goes away. It could be metal stains.
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    Mod Squad jblizzle's Avatar
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    Re: Vinyl IGP with fiberglass steps - blistering, stains, CH

    As was stated in your other post, fiberglass can have problems when the CH is low ... it is actually the CSI (Calcite Saturation Index) that is important. You can use the poolcalculator.com to determine your CSI. For example, with the numbers you provided, the CSI is -0.59 which is at the very low end of the recommended range for plaster pools. So, it too could be causing a problem with your fiberglass.

    If you look at the Recommended levels in Pool School: pool-school/recommended_levels

    You can see that vinyl there is a minimum of 50ppm for CH listed (although lower is fine)
    For fiberglass the minimum is 220ppm, while plaster is 250ppm.

    These are suggestions and really it is the CSI that is important. My pebble pool had a CH of around 120ppm for awhile, but I compensated by keeping the pH higher.

    So, maybe we should be a little more careful saying the CH does not matter for vinyl pools, when in fact is may matter if you have fiberglass steps or coves.
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    Re: Did low calcium cause my fiberglass steps to blister?

    Ok, so I really appreciate you guys getting back on this. I'm going to try the chlorine puck and the vitamin C tab and see which might be successful with the stains. I'll report back with progress. As far as the blisters are concerned I guess I'm stuck with them - likely nothing structural yet (from the info I've been able to find).

    I did take a run through the calc this morning and was doing some what'if's with the numebrs for CSI. I'll likley boost the CH a bit to see if I can get the CSI closer to 0 and go from there.

    If anyone else had ideas of comment please keep them coming.
    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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    Mod Squad jblizzle's Avatar
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    Re: Did low calcium cause my fiberglass steps to blister?

    I asked about the relationship of CH with fiberglass toward some of the forum experts and got this interesting response:
    Quote Originally Posted by JasonLion
    The idea that fiberglass pools need CH in the first place has only tenuous support. There certainly isn't any indication that low CH would cause blistering. The thought behind using CH with fiberglass has mostly to do with the long term stability of the gelcoat based on a fairly causal conversation with a single engineer working at a gelcoat company. CH can also help reduce metal staining on fiberglass surfaces (which is confirmed).

    There is a through discussion of the cause of blistering here. No mention of CH is ever made.
    Jason, TFP Moderator
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    Re: How to add calcium chloride to a vinyl pool?

    Quote Originally Posted by bobodaclown
    Try rubbing with a chlorine puck, see if it goes away. It could be algae. It might take some scrubbing. Have you tried brushing them with a high chlorine level.
    Try rubbing with a vitamin C tablet, see if it goes away. It could be metal stains.
    Yep, what bobodaclown said ^^^^^ try testing to determine if organic or metal stains.
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    Re: Did low calcium cause my fiberglass steps to blister?

    Quote Originally Posted by jblizzle
    I asked about the relationship of CH with fiberglass toward some of the forum experts and got this interesting response:
    Quote Originally Posted by JasonLion
    The idea that fiberglass pools need CH in the first place has only tenuous support. There certainly isn't any indication that low CH would cause blistering. The thought behind using CH with fiberglass has mostly to do with the long term stability of the gelcoat based on a fairly causal conversation with a single engineer working at a gelcoat company. CH can also help reduce metal staining on fiberglass surfaces (which is confirmed).

    There is a through discussion of the cause of blistering here. No mention of CH is ever made.

    Great read - I wonder if the question was rephrased and "asked about the relationship of CSI with fiberglass " what the response would be .... or perhaps that was answered definitively above ??
    29,700 Gallon Vinyl Roman End, Sta-Rite Max-Therm-400HD gas heater, Sta-Rite S7M120 cartridge filter, Pool Pilot DIG-220 SWG

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